cpython: 549d8d3297f2 (original) (raw)
Mercurial > cpython
changeset 84522:549d8d3297f2
Issue #18408: Fix _PyMem_DebugRealloc() Don't mark old extra memory dead before calling realloc(). realloc() can fail and realloc() must not touch the original buffer on failure. So mark old extra memory dead only on success if the new buffer did not move (has the same address). [#18408]
| Victor Stinner victor.stinner@gmail.com | |
|---|---|
| date | Tue, 09 Jul 2013 00:44:43 +0200 |
| parents | d605c6b8095c |
| children | c91e7f707562 |
| files | Objects/obmalloc.c |
| diffstat | 1 files changed, 8 insertions(+), 6 deletions(-)[+] [-] Objects/obmalloc.c 14 |
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--- a/Objects/obmalloc.c +++ b/Objects/obmalloc.c @@ -1780,7 +1780,7 @@ static void * _PyMem_DebugRealloc(void *ctx, void *p, size_t nbytes) { debug_alloc_api_t *api = (debug_alloc_api_t *)ctx;
- uchar *q = (uchar *)p, oldq; uchar tail; size_t total; / nbytes + 4SST */ size_t original_nbytes; @@ -1797,24 +1797,26 @@ static void / overflow: can't represent total as a size_t */ return NULL;
- if (nbytes < original_nbytes) {
/* shrinking: mark old extra memory dead */[](#l1.17)memset(q + nbytes, DEADBYTE, original_nbytes - nbytes + 2*SST);[](#l1.18)- }
- /* 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; q = (uchar )api->alloc.realloc(api->alloc.ctx, q - 2SST, total); if (q == NULL) return NULL;
- if (q == oldq && nbytes < original_nbytes) {
/* shrinking: mark old extra memory dead */[](#l1.31)memset(q + nbytes, DEADBYTE, original_nbytes - nbytes);[](#l1.32)- }
+ write_size_t(q, nbytes); assert(q[SST] == (uchar)api->api_id); for (i = 1; i < SST; ++i) assert(q[SST + i] == FORBIDDENBYTE); q += 2*SST; + tail = q + nbytes; memset(tail, FORBIDDENBYTE, SST); write_size_t(tail + SST, serialno);