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SubjectRe: [PATCH -next 1/2] ext4: fix potential memory leak in ext4_fc_record_regions()
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Hello,

Le 19/09/2022 à 16:40, Ye Bin a écrit :
> As krealloc may return NULL, in this case 'state->fc_regions' may not be
> freed by krealloc, but 'state->fc_regions' already set NULL. Then will
> lead to 'state->fc_regions' memory leak.
>
> Signed-off-by: Ye Bin <yebin10@huawei.com>
> ---
> fs/ext4/fast_commit.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
> index 9217a588afd1..cc8c8db075ba 100644
> --- a/fs/ext4/fast_commit.c
> +++ b/fs/ext4/fast_commit.c
> @@ -1677,15 +1677,17 @@ int ext4_fc_record_regions(struct super_block *sb, int ino,
> if (replay && state->fc_regions_used != state->fc_regions_valid)
> state->fc_regions_used = state->fc_regions_valid;
> if (state->fc_regions_used == state->fc_regions_size) {
> + struct ext4_fc_alloc_region *fc_regions;
> +
> state->fc_regions_size +=
> EXT4_FC_REPLAY_REALLOC_INCREMENT;
> - state->fc_regions = krealloc(
> - state->fc_regions,
> - state->fc_regions_size *
> - sizeof(struct ext4_fc_alloc_region),
> - GFP_KERNEL);
> - if (!state->fc_regions)
> + fc_regions = krealloc(state->fc_regions,
> + state->fc_regions_size *
> + sizeof(struct ext4_fc_alloc_region),
> + GFP_KERNEL);
> + if (!fc_regions)

Would it not be safer to restore state->fc_regions_size to its previous
value in that case to keep consistency between size value and allocated
size (or to update state->fc_regions_size only after allocation as it is
done in second part of this patch) ?

> return -ENOMEM;
> + state->fc_regions = fc_regions;
> }
> region = &state->fc_regions[state->fc_regions_used++];
> region->ino = ino;

Regards,

Damien

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