reallocating to a smaller-sized allocation. Fix this issue. Noticed by: alc Reviewed by: alc Approved by: zml (mentor) MFC after: 3 weeks
465 lines
14 KiB
C
465 lines
14 KiB
C
/*-
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* Copyright (c) 2005, Bosko Milekic <bmilekic@FreeBSD.org>.
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* Copyright (c) 2010 Isilon Systems, Inc. (http://www.isilon.com/)
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/*
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* MemGuard is a simple replacement allocator for debugging only
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* which provides ElectricFence-style memory barrier protection on
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* objects being allocated, and is used to detect tampering-after-free
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* scenarios.
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*
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* See the memguard(9) man page for more information on using MemGuard.
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*/
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#include "opt_vm.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/types.h>
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#include <sys/queue.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/malloc.h>
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#include <sys/sysctl.h>
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#include <vm/vm.h>
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#include <vm/uma.h>
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#include <vm/vm_param.h>
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#include <vm/vm_page.h>
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#include <vm/vm_map.h>
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#include <vm/vm_object.h>
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#include <vm/vm_extern.h>
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#include <vm/memguard.h>
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SYSCTL_NODE(_vm, OID_AUTO, memguard, CTLFLAG_RW, NULL, "MemGuard data");
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/*
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* The vm_memguard_divisor variable controls how much of kmem_map should be
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* reserved for MemGuard.
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*/
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static u_int vm_memguard_divisor;
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SYSCTL_UINT(_vm_memguard, OID_AUTO, divisor, CTLFLAG_RDTUN,
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&vm_memguard_divisor,
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0, "(kmem_size/memguard_divisor) == memguard submap size");
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/*
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* Short description (ks_shortdesc) of memory type to monitor.
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*/
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static char vm_memguard_desc[128] = "";
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static struct malloc_type *vm_memguard_mtype = NULL;
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TUNABLE_STR("vm.memguard.desc", vm_memguard_desc, sizeof(vm_memguard_desc));
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static int
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memguard_sysctl_desc(SYSCTL_HANDLER_ARGS)
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{
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char desc[sizeof(vm_memguard_desc)];
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int error;
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strlcpy(desc, vm_memguard_desc, sizeof(desc));
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error = sysctl_handle_string(oidp, desc, sizeof(desc), req);
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if (error != 0 || req->newptr == NULL)
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return (error);
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mtx_lock(&malloc_mtx);
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/*
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* If mtp is NULL, it will be initialized in memguard_cmp().
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*/
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vm_memguard_mtype = malloc_desc2type(desc);
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strlcpy(vm_memguard_desc, desc, sizeof(vm_memguard_desc));
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mtx_unlock(&malloc_mtx);
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return (error);
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}
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SYSCTL_PROC(_vm_memguard, OID_AUTO, desc,
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CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 0,
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memguard_sysctl_desc, "A", "Short description of memory type to monitor");
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static vm_map_t memguard_map = NULL;
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static vm_offset_t memguard_cursor;
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static vm_size_t memguard_mapsize;
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static vm_size_t memguard_physlimit;
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static u_long memguard_wasted;
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static u_long memguard_wrap;
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static u_long memguard_succ;
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static u_long memguard_fail_kva;
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static u_long memguard_fail_pgs;
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, cursor, CTLFLAG_RD,
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&memguard_cursor, 0, "MemGuard cursor");
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, mapsize, CTLFLAG_RD,
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&memguard_mapsize, 0, "MemGuard private vm_map size");
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, phys_limit, CTLFLAG_RD,
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&memguard_physlimit, 0, "Limit on MemGuard memory consumption");
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, wasted, CTLFLAG_RD,
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&memguard_wasted, 0, "Excess memory used through page promotion");
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, wrapcnt, CTLFLAG_RD,
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&memguard_wrap, 0, "MemGuard cursor wrap count");
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, numalloc, CTLFLAG_RD,
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&memguard_succ, 0, "Count of successful MemGuard allocations");
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, fail_kva, CTLFLAG_RD,
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&memguard_fail_kva, 0, "MemGuard failures due to lack of KVA");
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, fail_pgs, CTLFLAG_RD,
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&memguard_fail_pgs, 0, "MemGuard failures due to lack of pages");
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#define MG_GUARD 0x001
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#define MG_ALLLARGE 0x002
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static int memguard_options = MG_GUARD;
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TUNABLE_INT("vm.memguard.options", &memguard_options);
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SYSCTL_INT(_vm_memguard, OID_AUTO, options, CTLFLAG_RW,
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&memguard_options, 0,
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"MemGuard options:\n"
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"\t0x001 - add guard pages around each allocation\n"
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"\t0x002 - always use MemGuard for allocations over a page");
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static u_int memguard_minsize;
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static u_long memguard_minsize_reject;
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SYSCTL_UINT(_vm_memguard, OID_AUTO, minsize, CTLFLAG_RW,
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&memguard_minsize, 0, "Minimum size for page promotion");
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, minsize_reject, CTLFLAG_RD,
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&memguard_minsize_reject, 0, "# times rejected for size");
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static u_int memguard_frequency;
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static u_long memguard_frequency_hits;
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TUNABLE_INT("vm.memguard.frequency", &memguard_frequency);
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SYSCTL_UINT(_vm_memguard, OID_AUTO, frequency, CTLFLAG_RW,
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&memguard_frequency, 0, "Times in 100000 that MemGuard will randomly run");
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SYSCTL_ULONG(_vm_memguard, OID_AUTO, frequency_hits, CTLFLAG_RD,
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&memguard_frequency_hits, 0, "# times MemGuard randomly chose");
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/*
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* Return a fudged value to be used for vm_kmem_size for allocating
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* the kmem_map. The memguard memory will be a submap.
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*/
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unsigned long
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memguard_fudge(unsigned long km_size, unsigned long km_max)
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{
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u_long mem_pgs = cnt.v_page_count;
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vm_memguard_divisor = 10;
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TUNABLE_INT_FETCH("vm.memguard.divisor", &vm_memguard_divisor);
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/* Pick a conservative value if provided value sucks. */
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if ((vm_memguard_divisor <= 0) ||
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((km_size / vm_memguard_divisor) == 0))
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vm_memguard_divisor = 10;
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/*
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* Limit consumption of physical pages to
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* 1/vm_memguard_divisor of system memory. If the KVA is
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* smaller than this then the KVA limit comes into play first.
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* This prevents memguard's page promotions from completely
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* using up memory, since most malloc(9) calls are sub-page.
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*/
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memguard_physlimit = (mem_pgs / vm_memguard_divisor) * PAGE_SIZE;
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/*
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* We want as much KVA as we can take safely. Use at most our
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* allotted fraction of kmem_max. Limit this to twice the
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* physical memory to avoid using too much memory as pagetable
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* pages.
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*/
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memguard_mapsize = km_max / vm_memguard_divisor;
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/* size must be multiple of PAGE_SIZE */
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memguard_mapsize = round_page(memguard_mapsize);
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if (memguard_mapsize / (2 * PAGE_SIZE) > mem_pgs)
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memguard_mapsize = mem_pgs * 2 * PAGE_SIZE;
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if (km_size + memguard_mapsize > km_max)
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return (km_max);
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return (km_size + memguard_mapsize);
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}
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/*
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* Initialize the MemGuard mock allocator. All objects from MemGuard come
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* out of a single VM map (contiguous chunk of address space).
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*/
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void
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memguard_init(vm_map_t parent_map)
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{
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vm_offset_t base, limit;
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memguard_map = kmem_suballoc(parent_map, &base, &limit,
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memguard_mapsize, FALSE);
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memguard_map->system_map = 1;
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KASSERT(memguard_mapsize == limit - base,
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("Expected %lu, got %lu", (u_long)memguard_mapsize,
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(u_long)(limit - base)));
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memguard_cursor = base;
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printf("MEMGUARD DEBUGGING ALLOCATOR INITIALIZED:\n");
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printf("\tMEMGUARD map base: 0x%lx\n", (u_long)base);
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printf("\tMEMGUARD map limit: 0x%lx\n", (u_long)limit);
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printf("\tMEMGUARD map size: %jd KBytes\n",
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(uintmax_t)memguard_mapsize >> 10);
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}
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/*
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* Run things that can't be done as early as memguard_init().
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*/
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static void
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memguard_sysinit(void)
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{
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struct sysctl_oid_list *parent;
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parent = SYSCTL_STATIC_CHILDREN(_vm_memguard);
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SYSCTL_ADD_ULONG(NULL, parent, OID_AUTO, "mapstart", CTLFLAG_RD,
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&memguard_map->min_offset, "MemGuard KVA base");
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SYSCTL_ADD_ULONG(NULL, parent, OID_AUTO, "maplimit", CTLFLAG_RD,
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&memguard_map->max_offset, "MemGuard KVA end");
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SYSCTL_ADD_ULONG(NULL, parent, OID_AUTO, "mapused", CTLFLAG_RD,
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&memguard_map->size, "MemGuard KVA used");
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}
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SYSINIT(memguard, SI_SUB_KLD, SI_ORDER_ANY, memguard_sysinit, NULL);
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/*
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* v2sizep() converts a virtual address of the first page allocated for
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* an item to a pointer to u_long recording the size of the original
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* allocation request.
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*
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* This routine is very similar to those defined by UMA in uma_int.h.
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* The difference is that this routine stores the originally allocated
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* size in one of the page's fields that is unused when the page is
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* wired rather than the object field, which is used.
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*/
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static u_long *
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v2sizep(vm_offset_t va)
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{
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struct vm_page *p;
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p = PHYS_TO_VM_PAGE(pmap_kextract(va));
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KASSERT(p->wire_count != 0 && p->queue == PQ_NONE,
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("MEMGUARD: Expected wired page %p in vtomgfifo!", p));
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return ((u_long *)&p->pageq.tqe_next);
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}
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/*
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* Allocate a single object of specified size with specified flags
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* (either M_WAITOK or M_NOWAIT).
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*/
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void *
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memguard_alloc(unsigned long req_size, int flags)
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{
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vm_offset_t addr;
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u_long size_p, size_v;
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int do_guard, rv;
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size_p = round_page(req_size);
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if (size_p == 0)
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return (NULL);
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/*
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* To ensure there are holes on both sides of the allocation,
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* request 2 extra pages of KVA. We will only actually add a
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* vm_map_entry and get pages for the original request. Save
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* the value of memguard_options so we have a consistent
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* value.
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*/
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size_v = size_p;
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do_guard = (memguard_options & MG_GUARD) != 0;
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if (do_guard)
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size_v += 2 * PAGE_SIZE;
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vm_map_lock(memguard_map);
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/*
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* When we pass our memory limit, reject sub-page allocations.
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* Page-size and larger allocations will use the same amount
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* of physical memory whether we allocate or hand off to
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* uma_large_alloc(), so keep those.
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*/
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if (memguard_map->size >= memguard_physlimit &&
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req_size < PAGE_SIZE) {
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addr = (vm_offset_t)NULL;
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memguard_fail_pgs++;
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goto out;
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}
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/*
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* Keep a moving cursor so we don't recycle KVA as long as
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* possible. It's not perfect, since we don't know in what
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* order previous allocations will be free'd, but it's simple
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* and fast, and requires O(1) additional storage if guard
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* pages are not used.
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*
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* XXX This scheme will lead to greater fragmentation of the
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* map, unless vm_map_findspace() is tweaked.
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*/
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for (;;) {
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rv = vm_map_findspace(memguard_map, memguard_cursor,
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size_v, &addr);
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if (rv == KERN_SUCCESS)
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break;
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/*
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* The map has no space. This may be due to
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* fragmentation, or because the cursor is near the
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* end of the map.
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*/
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if (memguard_cursor == vm_map_min(memguard_map)) {
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memguard_fail_kva++;
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addr = (vm_offset_t)NULL;
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goto out;
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}
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memguard_wrap++;
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memguard_cursor = vm_map_min(memguard_map);
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}
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if (do_guard)
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addr += PAGE_SIZE;
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rv = kmem_back(memguard_map, addr, size_p, flags);
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if (rv != KERN_SUCCESS) {
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memguard_fail_pgs++;
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addr = (vm_offset_t)NULL;
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goto out;
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}
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memguard_cursor = addr + size_p;
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*v2sizep(trunc_page(addr)) = req_size;
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memguard_succ++;
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if (req_size < PAGE_SIZE) {
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memguard_wasted += (PAGE_SIZE - req_size);
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if (do_guard) {
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/*
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* Align the request to 16 bytes, and return
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* an address near the end of the page, to
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* better detect array overrun.
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*/
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req_size = roundup2(req_size, 16);
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addr += (PAGE_SIZE - req_size);
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}
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}
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out:
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vm_map_unlock(memguard_map);
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return ((void *)addr);
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}
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int
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is_memguard_addr(void *addr)
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{
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vm_offset_t a = (vm_offset_t)(uintptr_t)addr;
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return (a >= memguard_map->min_offset && a < memguard_map->max_offset);
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}
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/*
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* Free specified single object.
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*/
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void
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memguard_free(void *ptr)
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{
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vm_offset_t addr;
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u_long req_size, size;
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char *temp;
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int i;
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addr = trunc_page((uintptr_t)ptr);
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req_size = *v2sizep(addr);
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size = round_page(req_size);
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/*
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* Page should not be guarded right now, so force a write.
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* The purpose of this is to increase the likelihood of
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* catching a double-free, but not necessarily a
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* tamper-after-free (the second thread freeing might not
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* write before freeing, so this forces it to and,
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* subsequently, trigger a fault).
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*/
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temp = ptr;
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for (i = 0; i < size; i += PAGE_SIZE)
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temp[i] = 'M';
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/*
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* This requires carnal knowledge of the implementation of
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* kmem_free(), but since we've already replaced kmem_malloc()
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* above, it's not really any worse. We want to use the
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* vm_map lock to serialize updates to memguard_wasted, since
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* we had the lock at increment.
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*/
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vm_map_lock(memguard_map);
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if (req_size < PAGE_SIZE)
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memguard_wasted -= (PAGE_SIZE - req_size);
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(void)vm_map_delete(memguard_map, addr, addr + size);
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vm_map_unlock(memguard_map);
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}
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/*
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* Re-allocate an allocation that was originally guarded.
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*/
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void *
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memguard_realloc(void *addr, unsigned long size, struct malloc_type *mtp,
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int flags)
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{
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void *newaddr;
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u_long old_size;
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/*
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* Allocate the new block. Force the allocation to be guarded
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* as the original may have been guarded through random
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* chance, and that should be preserved.
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*/
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if ((newaddr = memguard_alloc(size, flags)) == NULL)
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return (NULL);
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/* Copy over original contents. */
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old_size = *v2sizep(trunc_page((uintptr_t)addr));
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bcopy(addr, newaddr, min(size, old_size));
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memguard_free(addr);
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return (newaddr);
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}
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int
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memguard_cmp(struct malloc_type *mtp, unsigned long size)
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{
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if (size < memguard_minsize) {
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memguard_minsize_reject++;
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return (0);
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}
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if ((memguard_options & MG_ALLLARGE) != 0 && size >= PAGE_SIZE)
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return (1);
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if (memguard_frequency > 0 &&
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(random() % 100000) < memguard_frequency) {
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memguard_frequency_hits++;
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return (1);
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}
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#if 1
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/*
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* The safest way of comparsion is to always compare short description
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* string of memory type, but it is also the slowest way.
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*/
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return (strcmp(mtp->ks_shortdesc, vm_memguard_desc) == 0);
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#else
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/*
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* If we compare pointers, there are two possible problems:
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* 1. Memory type was unloaded and new memory type was allocated at the
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* same address.
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* 2. Memory type was unloaded and loaded again, but allocated at a
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* different address.
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*/
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if (vm_memguard_mtype != NULL)
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return (mtp == vm_memguard_mtype);
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if (strcmp(mtp->ks_shortdesc, vm_memguard_desc) == 0) {
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vm_memguard_mtype = mtp;
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return (1);
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}
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return (0);
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#endif
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}
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