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SubjectRe: [PATCH 01/10] ext4: correct grp validation in ext4_mb_good_group
Kemeng Shi <shikemeng@huaweicloud.com> writes:

> Group corruption check will access memory of grp and will trigger kernel
> crash if grp is NULL. So do NULL check before corruption check.
>

Fixes: 5354b2af3406 ("ext4: allow ext4_get_group_info() to fail")

> Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
> ---
> fs/ext4/mballoc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 3ab37533349f..90ffabac100b 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -2554,7 +2554,7 @@ static bool ext4_mb_good_group(struct ext4_allocation_context *ac,
>
> BUG_ON(cr < CR_POWER2_ALIGNED || cr >= EXT4_MB_NUM_CRS);
>
> - if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp) || !grp))
> + if (!grp || unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp)))

maybe like below?
if (unlikely(!grp || EXT4_MB_GRP_BBITMAP_CORRUPT(grp)))

-ritesh

> return false;
>
> free = grp->bb_free;
> --
> 2.30.0

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