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The realloc case for memguard(9) will copy too many bytes when

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reallocating to a smaller-sized allocation.  Fix this issue.

Noticed by:     alc
Reviewed by:    alc
Approved by:    zml (mentor)
MFC after:      3 weeks
This commit is contained in:
Matthew D Fleming 2010-08-31 16:57:58 +00:00
parent b2a237be5c
commit 6d3ed393d6
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=212058
3 changed files with 29 additions and 9 deletions
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11
sys/kern/kern_malloc.c
View File

@ -566,11 +566,8 @@ realloc(void *addr, unsigned long size, struct malloc_type *mtp, int flags)
*/
#ifdef DEBUG_MEMGUARD
if (is_memguard_addr(addr)) {
slab = NULL;
alloc = size;
goto remalloc;
}
if (is_memguard_addr(addr))
return (memguard_realloc(addr, size, mtp, flags));
#endif
#ifdef DEBUG_REDZONE
@ -595,10 +592,6 @@ realloc(void *addr, unsigned long size, struct malloc_type *mtp, int flags)
return (addr);
#endif /* !DEBUG_REDZONE */
#ifdef DEBUG_MEMGUARD
remalloc:
#endif
/* Allocate a new, bigger (or smaller) block */
if ((newaddr = malloc(size, mtp, flags)) == NULL)
return (NULL);

25
sys/vm/memguard.c
View File

@ -399,6 +399,31 @@ memguard_free(void *ptr)
vm_map_unlock(memguard_map);
}
/*
* Re-allocate an allocation that was originally guarded.
*/
void *
memguard_realloc(void *addr, unsigned long size, struct malloc_type *mtp,
int flags)
{
void *newaddr;
u_long old_size;
/*
* Allocate the new block. Force the allocation to be guarded
* as the original may have been guarded through random
* chance, and that should be preserved.
*/
if ((newaddr = memguard_alloc(size, flags)) == NULL)
return (NULL);
/* Copy over original contents. */
old_size = *v2sizep(trunc_page((uintptr_t)addr));
bcopy(addr, newaddr, min(size, old_size));
memguard_free(addr);
return (newaddr);
}
int
memguard_cmp(struct malloc_type *mtp, unsigned long size)
{

2
sys/vm/memguard.h
View File

@ -38,6 +38,7 @@ struct vm_map;
unsigned long memguard_fudge(unsigned long, unsigned long);
void memguard_init(struct vm_map *);
void *memguard_alloc(unsigned long, int);
void *memguard_realloc(void *, unsigned long, struct malloc_type *, int);
void memguard_free(void *);
int memguard_cmp(struct malloc_type *, unsigned long);
int is_memguard_addr(void *);
@ -45,6 +46,7 @@ int is_memguard_addr(void *);
#define memguard_fudge(size, xxx) (size)
#define memguard_init(map) do { } while (0)
#define memguard_alloc(size, flags) NULL
#define memguard_realloc(a, s, mtp, f) NULL
#define memguard_free(addr) do { } while (0)
#define memguard_cmp(mtp, size) 0
#define is_memguard_addr(addr) 0