Re: [PATCH] ksmbd: fix possible memory leak in smb2_lock()

From: Hangyu Hua <hbh25y@gmail.com>
To: Namjae Jeon <linkinjeon@kernel.org>
Cc: sfrench@samba.org, senozhatsky@chromium.org, tom@talpey.com,
	hyc.lee@gmail.com, lsahlber@redhat.com,
	linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ksmbd: fix possible memory leak in smb2_lock()
Date: Mon, 6 Feb 2023 10:33:00 +0800	[thread overview]
Message-ID: <3558ad88-9846-b3f1-e5f8-3370cda6d185@gmail.com> (raw)
In-Reply-To: <CAKYAXd-hZ=7uiaN0khsUKw6wCxVo_kfxyUdy9advVro6hahaFg@mail.gmail.com>

On 4/2/2023 18:10, Namjae Jeon wrote:
> 2023-02-01 17:10 GMT+09:00, Hangyu Hua <hbh25y@gmail.com>:
>> argv needs to be free when setup_async_work fails or when the current
>> process is woken up.
>>
>> Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
>> Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
>> ---
>>   fs/ksmbd/smb2pdu.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
>> index d681f91947d9..5b7668c04f76 100644
>> --- a/fs/ksmbd/smb2pdu.c
>> +++ b/fs/ksmbd/smb2pdu.c
>> @@ -7050,6 +7050,7 @@ int smb2_lock(struct ksmbd_work *work)
>>   						      smb2_remove_blocked_lock,
>>   						      argv);
>>   				if (rc) {
>> +					kfree(argv);
>>   					err = -ENOMEM;
>>   					goto out;
>>   				}
>> @@ -7061,6 +7062,8 @@ int smb2_lock(struct ksmbd_work *work)
>>
>>   				ksmbd_vfs_posix_lock_wait(flock);
>>
>> +				work->cancel_fn = NULL;
>> +				kfree(argv);
> This change seems to causes a NULL pointer dereference issue in
> set_close_state_blocked_works(). It is right to free it and set NULL
> after removing entry from list.

I get it. I will send a v2.

Thanks,
Hangyu
>>   				if (work->state != KSMBD_WORK_ACTIVE) {
>>   					list_del(&smb_lock->llist);
>>   					spin_lock(&work->conn->llist_lock);
>> --
>> 2.34.1
>>
>>