linux-kernel - Re: [PATCH] ksmbd: fix possible memory leak in smb2

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Date:   Sat, 4 Feb 2023 19:10:08 +0900
From:   Namjae Jeon <linkinjeon@...nel.org>
To:     Hangyu Hua <hbh25y@...il.com>
Cc:     sfrench@...ba.org, senozhatsky@...omium.org, tom@...pey.com,
        hyc.lee@...il.com, lsahlber@...hat.com, linux-cifs@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ksmbd: fix possible memory leak in smb2_lock()

2023-02-01 17:10 GMT+09:00, Hangyu Hua <hbh25y@...il.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@...il.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.
>  				if (work->state != KSMBD_WORK_ACTIVE) {
>  					list_del(&smb_lock->llist);
>  					spin_lock(&work->conn->llist_lock);
> --
> 2.34.1
>
>