[PATCH master] dlmalloc: Fix integer overflow in request2size()
Ahmad Fatoum
a.fatoum at pengutronix.de
Mon Nov 18 23:15:25 PST 2024
From: Richard Weinberger <richard at nod.at>
req is of type size_t, casting it to long opens the door
for an integer overflow.
Values between LONG_MAX - (SIZE_SZ + MALLOC_ALIGN_MASK) - 1 and LONG_MAX
cause and overflow such that request2size() returns MINSIZE.
Fix by removing the cast.
The origin of the cast is unclear, it's in u-boot and ppcboot since ever
and predates the CVS history.
Doug Lea's original dlmalloc implementation also doesn't have it.
Signed-off-by: Richard Weinberger <richard at nod.at>
Link: https://lore.barebox.org/barebox/2561107.TLnPLrj5Ze@somecomputer/
Link: https://lore.kernel.org/all/20240802100846.16619-2-richard@nod.at/
Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
common/dlmalloc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index f92863f180d5..0ec7114c89d7 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -641,8 +641,8 @@ static inline mchunkptr mem2chunk(void *mem)
/* pad request bytes into a usable size */
#define request2size(req) \
- (((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \
- (long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \
+ ((((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \
+ (MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \
(((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK)))
/* Check if m has acceptable alignment */
--
2.39.5
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