2023-11-19 09:14:15

by Pierre Mariani

Subject: Re: [PATCH v2] ksmbd: prevent memory leak on error return

On 11/8/2023 5:17 PM, Zongmin Zhou wrote:
> When allocated memory for 'new' failed,just return
> will cause memory leak of 'ar'.
>
> v2: rollback iov_alloc_cnt when allocate memory failed.
>
> Fixes: 1819a9042999 ("ksmbd: reorganize ksmbd_iov_pin_rsp()")
>
> Reported-by: kernel test robot <[email protected]>
> Reported-by: Dan Carpenter <[email protected]>
> Closes: https://lore.kernel.org/r/[email protected]/
> Signed-off-by: Zongmin Zhou<[email protected]>
> ---
> fs/smb/server/ksmbd_work.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/smb/server/ksmbd_work.c b/fs/smb/server/ksmbd_work.c
> index a2ed441e837a..44bce4c56daf 100644
> --- a/fs/smb/server/ksmbd_work.c
> +++ b/fs/smb/server/ksmbd_work.c
> @@ -123,8 +123,11 @@ static int __ksmbd_iov_pin_rsp(struct ksmbd_work *work, void *ib, int len,
> new = krealloc(work->iov,
> sizeof(struct kvec) * work->iov_alloc_cnt,
> GFP_KERNEL | __GFP_ZERO);
> - if (!new)
> + if (!new) {
> + kfree(ar);
> + work->iov_alloc_cnt -= 4;
> return -ENOMEM;
> + }
> work->iov = new;
> }
>

A few lines above, ar is allocated inside the 'if (aux_size)' block.
If aux_size is falsy, isn't it possible that ar will be NULL hence
we should have 'if (ar) kfree(ar);'?

2023-11-19 14:17:39

by Namjae Jeon

Subject: Re: [PATCH v2] ksmbd: prevent memory leak on error return

2023-11-19 18:14 GMT+09:00, Pierre Mariani <[email protected]>:
> On 11/8/2023 5:17 PM, Zongmin Zhou wrote:
>> When allocated memory for 'new' failed,just return
>> will cause memory leak of 'ar'.
>>
>> v2: rollback iov_alloc_cnt when allocate memory failed.
>>
>> Fixes: 1819a9042999 ("ksmbd: reorganize ksmbd_iov_pin_rsp()")
>>
>> Reported-by: kernel test robot <[email protected]>
>> Reported-by: Dan Carpenter <[email protected]>
>> Closes: https://lore.kernel.org/r/[email protected]/
>> Signed-off-by: Zongmin Zhou<[email protected]>
>> ---
>> fs/smb/server/ksmbd_work.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/smb/server/ksmbd_work.c b/fs/smb/server/ksmbd_work.c
>> index a2ed441e837a..44bce4c56daf 100644
>> --- a/fs/smb/server/ksmbd_work.c
>> +++ b/fs/smb/server/ksmbd_work.c
>> @@ -123,8 +123,11 @@ static int __ksmbd_iov_pin_rsp(struct ksmbd_work
>> *work, void *ib, int len,
>> new = krealloc(work->iov,
>> sizeof(struct kvec) * work->iov_alloc_cnt,
>> GFP_KERNEL | __GFP_ZERO);
>> - if (!new)
>> + if (!new) {
>> + kfree(ar);
>> + work->iov_alloc_cnt -= 4;
>> return -ENOMEM;
>> + }
>> work->iov = new;
>> }
>>
>
> A few lines above, ar is allocated inside the 'if (aux_size)' block.
> If aux_size is falsy, isn't it possible that ar will be NULL hence
> we should have 'if (ar) kfree(ar);'?
We need to initialize ar to NULL on that case. And Passing a NULL
pointer to kfree is safe, So NULL check before kfree() is not needed.

Thanks.
>

2023-11-20 01:34:16

by Zongmin Zhou

Subject: Re: [PATCH v2] ksmbd: prevent memory leak on error return

On 2023/11/19 22:17, Namjae Jeon wrote:
> 2023-11-19 18:14 GMT+09:00, Pierre Mariani <[email protected]>:
>> On 11/8/2023 5:17 PM, Zongmin Zhou wrote:
>>> When allocated memory for 'new' failed,just return
>>> will cause memory leak of 'ar'.
>>>
>>> v2: rollback iov_alloc_cnt when allocate memory failed.
>>>
>>> Fixes: 1819a9042999 ("ksmbd: reorganize ksmbd_iov_pin_rsp()")
>>>
>>> Reported-by: kernel test robot <[email protected]>
>>> Reported-by: Dan Carpenter <[email protected]>
>>> Closes: https://lore.kernel.org/r/[email protected]/
>>> Signed-off-by: Zongmin Zhou<[email protected]>
>>> ---
>>> fs/smb/server/ksmbd_work.c | 5 ++++-
>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/smb/server/ksmbd_work.c b/fs/smb/server/ksmbd_work.c
>>> index a2ed441e837a..44bce4c56daf 100644
>>> --- a/fs/smb/server/ksmbd_work.c
>>> +++ b/fs/smb/server/ksmbd_work.c
>>> @@ -123,8 +123,11 @@ static int __ksmbd_iov_pin_rsp(struct ksmbd_work
>>> *work, void *ib, int len,
>>> new = krealloc(work->iov,
>>> sizeof(struct kvec) * work->iov_alloc_cnt,
>>> GFP_KERNEL | __GFP_ZERO);
>>> - if (!new)
>>> + if (!new) {
>>> + kfree(ar);
>>> + work->iov_alloc_cnt -= 4;
>>> return -ENOMEM;
>>> + }
>>> work->iov = new;
>>> }
>>>
>> A few lines above, ar is allocated inside the 'if (aux_size)' block.
>> If aux_size is falsy, isn't it possible that ar will be NULL hence
>> we should have 'if (ar) kfree(ar);'?
> We need to initialize ar to NULL on that case. And Passing a NULL
> pointer to kfree is safe, So NULL check before kfree() is not needed.
Yes, ar should be initialized to NULL to avoid the case of  aux_size
will be false.
Since kfree(NULL) is safe.
Should I  send another patch for this?

Best regards!
> Thanks.

2023-11-20 01:38:23

by Namjae Jeon

Subject: Re: [PATCH v2] ksmbd: prevent memory leak on error return

2023-11-20 10:33 GMT+09:00, Zongmin Zhou <[email protected]>:
>
> On 2023/11/19 22:17, Namjae Jeon wrote:
>> 2023-11-19 18:14 GMT+09:00, Pierre Mariani <[email protected]>:
>>> On 11/8/2023 5:17 PM, Zongmin Zhou wrote:
>>>> When allocated memory for 'new' failed,just return
>>>> will cause memory leak of 'ar'.
>>>>
>>>> v2: rollback iov_alloc_cnt when allocate memory failed.
>>>>
>>>> Fixes: 1819a9042999 ("ksmbd: reorganize ksmbd_iov_pin_rsp()")
>>>>
>>>> Reported-by: kernel test robot <[email protected]>
>>>> Reported-by: Dan Carpenter <[email protected]>
>>>> Closes: https://lore.kernel.org/r/[email protected]/
>>>> Signed-off-by: Zongmin Zhou<[email protected]>
>>>> ---
>>>> fs/smb/server/ksmbd_work.c | 5 ++++-
>>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/smb/server/ksmbd_work.c b/fs/smb/server/ksmbd_work.c
>>>> index a2ed441e837a..44bce4c56daf 100644
>>>> --- a/fs/smb/server/ksmbd_work.c
>>>> +++ b/fs/smb/server/ksmbd_work.c
>>>> @@ -123,8 +123,11 @@ static int __ksmbd_iov_pin_rsp(struct ksmbd_work
>>>> *work, void *ib, int len,
>>>> new = krealloc(work->iov,
>>>> sizeof(struct kvec) * work->iov_alloc_cnt,
>>>> GFP_KERNEL | __GFP_ZERO);
>>>> - if (!new)
>>>> + if (!new) {
>>>> + kfree(ar);
>>>> + work->iov_alloc_cnt -= 4;
>>>> return -ENOMEM;
>>>> + }
>>>> work->iov = new;
>>>> }
>>>>
>>> A few lines above, ar is allocated inside the 'if (aux_size)' block.
>>> If aux_size is falsy, isn't it possible that ar will be NULL hence
>>> we should have 'if (ar) kfree(ar);'?
>> We need to initialize ar to NULL on that case. And Passing a NULL
>> pointer to kfree is safe, So NULL check before kfree() is not needed.
> Yes, ar should be initialized to NULL to avoid the case of aux_size
> will be false.
> Since kfree(NULL) is safe.
> Should I send another patch for this?
I would appreciate it if you could do that.

>
> Best regards!
>> Thanks.
>
>