From 710111cc7c58f9b51be949fb9a30487372af5dd9 Mon Sep 17 00:00:00 2001 From: Chris Fallin Date: Thu, 14 May 2015 18:05:39 -0700 Subject: [PATCH] Bugfix: seeded_alloc() should not realloc() user-provided memory. --- upb/env.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/upb/env.c b/upb/env.c index 7fa333452a..0d146535cf 100644 --- a/upb/env.c +++ b/upb/env.c @@ -211,6 +211,8 @@ static size_t align_up(size_t size) { UPB_FORCEINLINE static void *seeded_alloc(void *ud, void *ptr, size_t oldsize, size_t size) { + UPB_UNUSED(ptr); + upb_seededalloc *a = ud; size = align_up(size); @@ -224,7 +226,14 @@ UPB_FORCEINLINE static void *seeded_alloc(void *ud, void *ptr, size_t oldsize, } else { // Slow path: fallback to other allocator. a->need_cleanup = true; - return a->alloc(a->alloc_ud, ptr, oldsize, size); + // Is `ptr` part of the user-provided initial block? Don't pass it to the + // default allocator if so; otherwise, it may try to realloc() the block. + char *chptr = ptr; + if (chptr >= a->mem_base && chptr < a->mem_limit) { + return a->alloc(a->alloc_ud, NULL, 0, size); + } else { + return a->alloc(a->alloc_ud, ptr, oldsize, size); + } } }