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

[Zongmin Zhou]

On 2023/11/19 22:17, Namjae Jeon wrote:
> 2023-11-19 18:14 GMT+09:00, Pierre Mariani <pierre.mariani@xxxxxxxxx>:
> > 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 <lkp@xxxxxxxxx>
> > > Reported-by: Dan Carpenter <error27@xxxxxxxxx>
> > > Closes: https://lore.kernel.org/r/202311031837.H3yo7JVl-lkp@xxxxxxxxx/
> > > Signed-off-by: Zongmin Zhou<zhouzongmin@xxxxxxxxxx>
> > > ---
> > >   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.