The patch titled
Subject: mm/fadvise.c: fix signed overflow UBSAN complaint
has been removed from the -mm tree. Its filename was
mm-fadvise-fix-signed-overflow-ubsan-complaint.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Subject: mm/fadvise.c: fix signed overflow UBSAN complaint
Signed integer overflow is undefined according to the C standard. The
overflow in ksys_fadvise64_64() is deliberate, but since it is signed
overflow, UBSAN complains:
UBSAN: Undefined behaviour in mm/fadvise.c:76:10
signed integer overflow:
4 + 9223372036854775805 cannot be represented in type 'long long int'
Use unsigned types to do math. Unsigned overflow is defined so UBSAN will
not complain about it. This patch doesn't change generated code.
[akpm@xxxxxxxxxxxxxxxxxxxx: add comment explaining the casts]
Link: http://lkml.kernel.org/r/20180629184453.7614-1-aryabinin@xxxxxxxxxxxxx
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Reported-by: <icytxw@xxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/fadvise.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/mm/fadvise.c~mm-fadvise-fix-signed-overflow-ubsan-complaint
+++ a/mm/fadvise.c
@@ -72,8 +72,12 @@ int ksys_fadvise64_64(int fd, loff_t off
goto out;
}
- /* Careful about overflows. Len == 0 means "as much as possible" */
- endbyte = offset + len;
+ /*
+ * Careful about overflows. Len == 0 means "as much as possible". Use
+ * unsigned math because signed overflows are undefined and UBSan
+ * complains.
+ */
+ endbyte = (u64)offset + (u64)len;
if (!len || endbyte < len)
endbyte = -1;
else
_
Patches currently in -mm which might be from aryabinin@xxxxxxxxxxxxx are
