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Make p_vaddr % p_align == p_offset % p_align for (some) TLS segments.

Browse Source 
See https://sourceware.org/bugzilla/show_bug.cgi?id=24606 for the test case.
See https://reviews.llvm.org/D64930 for the background and more discussion.

Also this fixes another bug in malloc_aligned() where total size of
the allocated memory might be not enough to fit the aligned requested
block after the initial pointer is incremented by the pointer size.

Reviewed by:	bdragon
Tested by:	antoine (exp-run PR 244866), bdragon, emaste
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Differential revision:	https://reviews.freebsd.org/D21163
This commit is contained in:
Konstantin Belousov 2020-04-04 22:37:50 +00:00
parent ff595bc3cd
commit 2f06c66ad5
4 changed files with 49 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
libexec/rtld-elf/map_object.c
View File

@ -313,6 +313,7 @@ map_object(int fd, const char *path, const struct stat *sb)
obj->tlsindex = ++tls_max_index;
obj->tlssize = phtls->p_memsz;
obj->tlsalign = phtls->p_align;
obj->tlspoffset = phtls->p_offset;
obj->tlsinitsize = phtls->p_filesz;
obj->tlsinit = mapbase + phtls->p_vaddr;
}

62
libexec/rtld-elf/rtld.c
View File

@ -1501,6 +1501,7 @@ digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
obj->tlsalign = ph->p_align;
obj->tlsinitsize = ph->p_filesz;
obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
obj->tlspoffset = ph->p_offset;
break;
case PT_GNU_STACK:
@ -4868,7 +4869,7 @@ allocate_tls(Obj_Entry *objs, void *oldtcb, size_t tcbsize, size_t tcbalign)
Elf_Addr addr;
Elf_Addr i;
size_t extra_size, maxalign, post_size, pre_size, tls_block_size;
size_t tls_init_align;
size_t tls_init_align, tls_init_offset;
if (oldtcb != NULL && tcbsize == TLS_TCB_SIZE)
return (oldtcb);
@ -4885,7 +4886,7 @@ allocate_tls(Obj_Entry *objs, void *oldtcb, size_t tcbsize, size_t tcbalign)
tls_block_size += pre_size + tls_static_space - TLS_TCB_SIZE - post_size;
/* Allocate whole TLS block */
tls_block = malloc_aligned(tls_block_size, maxalign);
tls_block = malloc_aligned(tls_block_size, maxalign, 0);
tcb = (Elf_Addr **)(tls_block + pre_size + extra_size);
if (oldtcb != NULL) {
@ -4909,15 +4910,21 @@ allocate_tls(Obj_Entry *objs, void *oldtcb, size_t tcbsize, size_t tcbalign)
for (obj = globallist_curr(objs); obj != NULL;
obj = globallist_next(obj)) {
if (obj->tlsoffset > 0) {
addr = (Elf_Addr)tcb + obj->tlsoffset;
if (obj->tlsinitsize > 0)
memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
if (obj->tlssize > obj->tlsinitsize)
memset((void*)(addr + obj->tlsinitsize), 0,
obj->tlssize - obj->tlsinitsize);
dtv[obj->tlsindex + 1] = addr;
if (obj->tlsoffset == 0)
continue;
tls_init_offset = obj->tlspoffset & (obj->tlsalign - 1);
addr = (Elf_Addr)tcb + obj->tlsoffset;
if (tls_init_offset > 0)
memset((void *)addr, 0, tls_init_offset);
if (obj->tlsinitsize > 0) {
memcpy((void *)(addr + tls_init_offset), obj->tlsinit,
obj->tlsinitsize);
}
if (obj->tlssize > obj->tlsinitsize) {
memset((void *)(addr + tls_init_offset + obj->tlsinitsize),
0, obj->tlssize - obj->tlsinitsize - tls_init_offset);
}
dtv[obj->tlsindex + 1] = addr;
}
}
@ -4975,7 +4982,7 @@ allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign)
size = round(tls_static_space, ralign) + round(tcbsize, ralign);
assert(tcbsize >= 2*sizeof(Elf_Addr));
tls = malloc_aligned(size, ralign);
tls = malloc_aligned(size, ralign, 0 /* XXX */);
dtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
segbase = (Elf_Addr)(tls + round(tls_static_space, ralign));
@ -5068,25 +5075,24 @@ free_tls(void *tls, size_t tcbsize __unused, size_t tcbalign)
void *
allocate_module_tls(int index)
{
Obj_Entry* obj;
char* p;
Obj_Entry *obj;
char *p;
TAILQ_FOREACH(obj, &obj_list, next) {
if (obj->marker)
continue;
if (obj->tlsindex == index)
break;
}
if (!obj) {
_rtld_error("Can't find module with TLS index %d", index);
rtld_die();
}
TAILQ_FOREACH(obj, &obj_list, next) {
if (obj->marker)
continue;
if (obj->tlsindex == index)
break;
}
if (obj == NULL) {
_rtld_error("Can't find module with TLS index %d", index);
rtld_die();
}
p = malloc_aligned(obj->tlssize, obj->tlsalign);
memcpy(p, obj->tlsinit, obj->tlsinitsize);
memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
return p;
p = malloc_aligned(obj->tlssize, obj->tlsalign, obj->tlspoffset);
memcpy(p, obj->tlsinit, obj->tlsinitsize);
memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
return (p);
}
bool

3
libexec/rtld-elf/rtld.h
View File

@ -163,6 +163,7 @@ typedef struct Struct_Obj_Entry {
size_t tlssize; /* Size of TLS block for this module */
size_t tlsoffset; /* Offset of static TLS block for this module */
size_t tlsalign; /* Alignment of static TLS block */
size_t tlspoffset; /* p_offset of the static TLS block */
caddr_t relro_page;
size_t relro_size;
@ -361,7 +362,7 @@ Obj_Entry *map_object(int, const char *, const struct stat *);
void *xcalloc(size_t, size_t);
void *xmalloc(size_t);
char *xstrdup(const char *);
void *malloc_aligned(size_t size, size_t align);
void *malloc_aligned(size_t size, size_t align, size_t offset);
void free_aligned(void *ptr);
extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
extern Elf_Sym sym_zero; /* For resolving undefined weak refs. */

18
libexec/rtld-elf/xmalloc.c
View File

@ -27,6 +27,7 @@
* $FreeBSD$
*/
#include <sys/param.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
@ -76,16 +77,21 @@ xstrdup(const char *str)
}
void *
malloc_aligned(size_t size, size_t align)
malloc_aligned(size_t size, size_t align, size_t offset)
{
void *mem, *res;
char *mem, *res;
uintptr_t x;
offset &= align - 1;
if (align < sizeof(void *))
align = sizeof(void *);
mem = xmalloc(size + sizeof(void *) + align - 1);
res = (void *)round((uintptr_t)mem + sizeof(void *), align);
*(void **)((uintptr_t)res - sizeof(void *)) = mem;
mem = xmalloc(size + 3 * align + offset);
x = roundup((uintptr_t)mem + sizeof(void *), align);
x += offset;
res = (void *)x;
x -= sizeof(void *);
memcpy((void *)x, &mem, sizeof(mem));
return (res);
}
@ -99,6 +105,6 @@ free_aligned(void *ptr)
return;
x = (uintptr_t)ptr;
x -= sizeof(void *);
mem = *(void **)x;
memcpy(&mem, (void *)x, sizeof(mem));
free(mem);
}