2022-09-19 14:30:30

by yebin (H)

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

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 <[email protected]>
---
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)
return -ENOMEM;
+ state->fc_regions = fc_regions;
}
region = &state->fc_regions[state->fc_regions_used++];
region->ino = ino;
--
2.31.1

2022-09-19 15:36:35

by Jan Kara

Subject: Re: [PATCH -next 1/2] ext4: fix potential memory leak in ext4_fc_record_regions()

On Mon 19-09-22 22:40:20, Ye Bin wrote:
> 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 <[email protected]>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <[email protected]>

Honza

> ---
> 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)
> return -ENOMEM;
> + state->fc_regions = fc_regions;
> }
> region = &state->fc_regions[state->fc_regions_used++];
> region->ino = ino;
> --
> 2.31.1
>
--
Jan Kara <[email protected]>
SUSE Labs, CR

2022-09-19 18:41:51

by Damien Guibouret

Subject: Re: [PATCH -next 1/2] ext4: fix potential memory leak in ext4_fc_record_regions()

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 <[email protected]>
> ---
> 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

2022-09-20 01:12:04

by yebin (H)

Subject: Re: [PATCH -next 1/2] ext4: fix potential memory leak in ext4_fc_record_regions()

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 <[email protected]>
>> ---
>> 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
>
> .
>

2022-09-20 18:35:06

by Damien Guibouret

Subject: Re: [PATCH -next 1/2] ext4: fix potential memory leak in ext4_fc_record_regions()

Hello,

Le 20/09/2022 à 03:07, yebin a écrit :
>
>
> 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 <[email protected]>
>>> ---
>>>   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.

There are at least two calls in ext4_ext_clear_bb (ext4/extents.c) that
do not check for return code of ext4_fc_record_regions. But perhaps
these are these calls that should be fixed.

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

Regards,

Damien