path: root/src/malloc/lite_malloc.c
diff options
authorRich Felker <>2015-06-22 18:50:09 +0000
committerRich Felker <>2015-06-22 18:50:09 +0000
commitba819787ee93ceae94efd274f7849e317c1bff58 (patch)
tree0de9857d6e6567934f23ffe1eb17ed4cee448d21 /src/malloc/lite_malloc.c
parent55d061f031085f24d138664c897791aebe9a2fab (diff)
fix calloc when __simple_malloc implementation is used
previously, calloc's implementation encoded assumptions about the implementation of malloc, accessing a size_t word just prior to the allocated memory to determine if it was obtained by mmap to optimize out the zero-filling. when __simple_malloc is used (static linking a program with no realloc/free), it doesn't matter if the result of this check is wrong, since all allocations are zero-initialized anyway. but the access could be invalid if it crosses a page boundary or if the pointer is not sufficiently aligned, which can happen for very small allocations. this patch fixes the issue by moving the zero-fill logic into malloc.c with the full malloc, as a new function named __malloc0, which is provided by a weak alias to __simple_malloc (which always gives zero-filled memory) when the full malloc is not in use.
Diffstat (limited to 'src/malloc/lite_malloc.c')
1 files changed, 1 insertions, 0 deletions
diff --git a/src/malloc/lite_malloc.c b/src/malloc/lite_malloc.c
index 008549d6..b09f30b0 100644
--- a/src/malloc/lite_malloc.c
+++ b/src/malloc/lite_malloc.c
@@ -47,3 +47,4 @@ void *__simple_malloc(size_t n)
weak_alias(__simple_malloc, malloc);
+weak_alias(__simple_malloc, malloc0);