linux-kernel - Re: [PATCH] ksmbd: fix leak of transform buffer on encrypt

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Message-ID: <CAKYAXd_9Vf+ZMhuf8ZWvsize3RJ0SvTWGuEsX11jA8r7tvmXmA@mail.gmail.com>
Date: Tue, 4 Nov 2025 20:51:12 +0900
From: Namjae Jeon <linkinjeon@...nel.org>
To: Qianchang Zhao <pioooooooooip@...il.com>
Cc: Steve French <smfrench@...il.com>, Sergey Senozhatsky <senozhatsky@...omium.org>, 
	Tom Talpey <tom@...pey.com>, linux-cifs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	gregkh@...uxfoundation.org, Zhitong Liu <liuzhitong1993@...il.com>, 
	stable@...r.kernel.org
Subject: Re: [PATCH] ksmbd: fix leak of transform buffer on encrypt_resp() failure

On Tue, Nov 4, 2025 at 7:03 PM Qianchang Zhao <pioooooooooip@...il.com> wrote:
>
> When encrypt_resp() fails at the send path, we only set
> STATUS_DATA_ERROR but leave the transform buffer allocated (work->tr_buf
> in this tree). Repeating this path leaks kernel memory and can lead to
> OOM (DoS) when encryption is required.
>
> Reproduced on: Linux v6.18-rc2 (self-built test kernel)
>
> Fix by freeing the transform buffer and forcing plaintext error reply.
>
> Reported-by: Qianchang Zhao <pioooooooooip@...il.com>
> Reported-by: Zhitong Liu <liuzhitong1993@...il.com>
> Cc: stable@...r.kernel.org
> Signed-off-by: Qianchang Zhao <pioooooooooip@...il.com>
> ---
>  fs/smb/server/server.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c
> index 7b01c7589..15dd13e76 100644
> --- a/fs/smb/server/server.c
> +++ b/fs/smb/server/server.c
> @@ -246,11 +246,11 @@ static void __handle_ksmbd_work(struct ksmbd_work *work,
>                 rc = conn->ops->encrypt_resp(work);
>                 if (rc < 0) {
>                         conn->ops->set_rsp_status(work, STATUS_DATA_ERROR);
> -                        work->encrypted = false;
> -                               if (work->tr_buf) {
> -                                       kvfree(work->tr_buf);
> -                                       work->tr_buf = NULL;
> -                                       }
> +                       work->encrypted = false;
> +                       if (work->tr_buf) {
> +                               kvfree(work->tr_buf);
> +                               work->tr_buf = NULL;
> +                       }
This patch seems to be broken or wrong. Please check the patch again.
Thanks!
>                 }
>         }
>         if (work->sess)
> --
> 2.34.1
>