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glibc/SOURCES/glibc-rh1871383-5.patch

36 lines
1.2 KiB

From b9cde4e3aa1ff338da7064daf1386b2f4a7351ba Mon Sep 17 00:00:00 2001
From: DJ Delorie <dj@redhat.com>
Date: Sat, 4 Apr 2020 01:44:56 -0400
Subject: malloc: ensure set_max_fast never stores zero [BZ #25733]
The code for set_max_fast() stores an "impossibly small value"
instead of zero, when the parameter is zero. However, for
small values of the parameter (ex: 1 or 2) the computation
results in a zero being stored anyway.
This patch checks for the parameter being small enough for the
computation to result in zero instead, so that a zero is never
stored.
key values which result in zero being stored:
x86-64: 1..7 (or other 64-bit)
i686: 1..11
armhfp: 1..3 (or other 32-bit)
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 6acb5ad43a..ee87ddbbf9 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -1632,7 +1632,7 @@ static INTERNAL_SIZE_T global_max_fast;
*/
#define set_max_fast(s) \
- global_max_fast = (((s) == 0) \
+ global_max_fast = (((size_t) (s) <= MALLOC_ALIGN_MASK - SIZE_SZ) \
? MIN_CHUNK_SIZE / 2 : ((s + SIZE_SZ) & ~MALLOC_ALIGN_MASK))
static inline INTERNAL_SIZE_T