commit e1c6431e42bc6b5619c78008cbe92730ead57bbf Author: Nick Mathewson nickm@torproject.org Date: Wed Nov 9 12:08:28 2011 -0500
Correct the handling of overflow behavior in smartlist_ensure_capacity
The old behavior was susceptible to the compiler optimizing out our assertion check, *and* could still overflow size_t on 32-bit systems even when it did work. --- changes/bug4230 | 5 +++++ src/common/container.c | 19 ++++++++++++++----- 2 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/changes/bug4230 b/changes/bug4230 new file mode 100644 index 0000000..c1ba584 --- /dev/null +++ b/changes/bug4230 @@ -0,0 +1,5 @@ + o Minor bugfixes: + - Resolve an integer overflow bug in smartlist_ensure_capacity. + Fixes bug 4230; bugfix on Tor 0.1.0.1-rc. Based on a patch by + Mansour Moufid. + diff --git a/src/common/container.c b/src/common/container.c index c741eb0..edfcd97 100644 --- a/src/common/container.c +++ b/src/common/container.c @@ -61,13 +61,22 @@ smartlist_clear(smartlist_t *sl) static INLINE void smartlist_ensure_capacity(smartlist_t *sl, int size) { +#if SIZEOF_SIZE_T > SIZEOF_INT +#define MAX_CAPACITY (INT_MAX) +#else +#define MAX_CAPACITY (int)((SIZE_MAX / (sizeof(void*)))) +#endif if (size > sl->capacity) { - int higher = sl->capacity * 2; - while (size > higher) - higher *= 2; - tor_assert(higher > 0); /* detect overflow */ + int higher = sl->capacity; + if (PREDICT_UNLIKELY(size > MAX_CAPACITY/2)) { + tor_assert(size <= MAX_CAPACITY); + higher = MAX_CAPACITY; + } else { + while (size > higher) + higher *= 2; + } sl->capacity = higher; - sl->list = tor_realloc(sl->list, sizeof(void*)*sl->capacity); + sl->list = tor_realloc(sl->list, sizeof(void*)*((size_t)sl->capacity)); } }