mirror of https://github.com/python/cpython
bpo-31626: Fixed a bug in debug memory allocator. (#3844)
Removed a code that incorrectly detected in-place resizing in realloc() and wrote to freed memory.
This commit is contained in:
parent
b9052a0f91
commit
b484d5606c
|
@ -0,0 +1,2 @@
|
|||
Fixed a bug in debug memory allocator. There was a write to freed memory
|
||||
after shrinking a memory block.
|
|
@ -1460,7 +1460,7 @@ static void *
|
|||
_PyMem_DebugRawRealloc(void *ctx, void *p, size_t nbytes)
|
||||
{
|
||||
debug_alloc_api_t *api = (debug_alloc_api_t *)ctx;
|
||||
uint8_t *q = (uint8_t *)p, *oldq;
|
||||
uint8_t *q = (uint8_t *)p;
|
||||
uint8_t *tail;
|
||||
size_t total; /* nbytes + 4*SST */
|
||||
size_t original_nbytes;
|
||||
|
@ -1477,20 +1477,11 @@ _PyMem_DebugRawRealloc(void *ctx, void *p, size_t nbytes)
|
|||
/* overflow: can't represent total as a Py_ssize_t */
|
||||
return NULL;
|
||||
|
||||
/* Resize and add decorations. We may get a new pointer here, in which
|
||||
* case we didn't get the chance to mark the old memory with DEADBYTE,
|
||||
* but we live with that.
|
||||
*/
|
||||
oldq = q;
|
||||
/* Resize and add decorations. */
|
||||
q = (uint8_t *)api->alloc.realloc(api->alloc.ctx, q - 2*SST, total);
|
||||
if (q == NULL)
|
||||
return NULL;
|
||||
|
||||
if (q == oldq && nbytes < original_nbytes) {
|
||||
/* shrinking: mark old extra memory dead */
|
||||
memset(q + nbytes, DEADBYTE, original_nbytes - nbytes);
|
||||
}
|
||||
|
||||
write_size_t(q, nbytes);
|
||||
assert(q[SST] == (uint8_t)api->api_id);
|
||||
for (i = 1; i < SST; ++i)
|
||||
|
|
Loading…
Reference in New Issue