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SubjectRe: [PATCH -next 1/2] ext4: fix potential memory leak in ext4_fc_record_regions()
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On 2022/9/20 2:40, Damien Guibouret wrote:
> 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) ?
>
Actually, If 'ext4_fc_record_regions()' return -ENOMEM, then will stop
replay journal.
'state->fc_regions_size' will not be used any more, so it's safe.
>> return -ENOMEM;
>> + state->fc_regions = fc_regions;
>> }
>> region = &state->fc_regions[state->fc_regions_used++];
>> region->ino = ino;
>
> Regards,
>
> Damien
>
> .
>

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