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CLEANUP: pools: move the write before free to the uaf-only function

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In UAF mode, pool_put_to_os() performs a write to the about-to-be-freed
memory area so as to make sure the page is properly mapped and catch a
possible double-free. However there's no point keeping that in an ifdef
in the generic function, because we now have a pool_free_area_uaf()
that is the UAF-specific version of pool_free_area() and the one that
is called immediately after this write. Let's move the code there, it
will be cleaner.
This commit is contained in:
Willy Tarreau 2022-12-08 09:29:42 +01:00
parent 94dbfedec1
commit 67f89c527f
1 changed files with 6 additions and 8 deletions
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14
src/pool.c
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@ -352,14 +352,6 @@ void *pool_get_from_os(struct pool_head *pool)
*/
void pool_put_to_os(struct pool_head *pool, void *ptr)
{
#ifdef DEBUG_UAF
/* This object will be released for real in order to detect a use after
* free. We also force a write to the area to ensure we crash on double
* free or free of a const area.
*/
*(uint32_t *)ptr = 0xDEADADD4;
#endif /* DEBUG_UAF */
pool_free_area(ptr, pool->alloc_sz);
_HA_ATOMIC_DEC(&pool->allocated);
}
@ -837,6 +829,12 @@ void pool_free_area_uaf(void *area, size_t size)
{
size_t pad = (4096 - size) & 0xFF0;
/* This object will be released for real in order to detect a use after
* free. We also force a write to the area to ensure we crash on double
* free or free of a const area.
*/
*(uint32_t *)area = 0xDEADADD4;
if (pad >= sizeof(void *) && *(void **)(area - sizeof(void *)) != area)
ABORT_NOW();