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ext4: avoid potential data overflow in next_linear_group 

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: 196e402adf ("ext4: improve cr 0 / cr 1 group scanning")
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20230801143204.2284343-3-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Kemeng Shi 2023-08-01 22:31:56 +08:00 committed by Theodore Ts'o
parent a9ce5993a0
commit 60c672b7f2
1 changed files with 3 additions and 2 deletions
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5
fs/ext4/mballoc.c
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@ -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;