This is a note to let you know that I've just added the patch titled
ext4: avoid potential data overflow in next_linear_group
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-avoid-potential-data-overflow-in-next_linear_gr.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7c4cf948c856a4026e8db8fc5a06409269898765
Author: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Date: Tue Aug 1 22:31:56 2023 +0800
ext4: avoid potential data overflow in next_linear_group
[ Upstream commit 60c672b7f2d1e5dd1774f2399b355c9314e709f8 ]
ngroups is ext4_group_t (unsigned int) while next_linear_group treat it
in int. If ngroups is bigger than max number described by int, it will
be treat as a negative number. Then "return group + 1 >= ngroups ? 0 :
group + 1;" may keep returning 0.
Switch int to ext4_group_t in next_linear_group to fix the overflow.
Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning")
Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230801143204.2284343-3-shikemeng@xxxxxxxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index b00b7adf1461d..a197ef71b7b02 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1080,8 +1080,9 @@ static inline int should_optimize_scan(struct ext4_allocation_context *ac)
* Return next linear group for allocation. If linear traversal should not be
* performed, this function just returns the same group
*/
-static int
-next_linear_group(struct ext4_allocation_context *ac, int group, int ngroups)
+static ext4_group_t
+next_linear_group(struct ext4_allocation_context *ac, ext4_group_t group,
+ ext4_group_t ngroups)
{
if (!should_optimize_scan(ac))
goto inc_and_return;
