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@gmail.com Reported-by: Zhitong Liu liuzhitong1993@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Qianchang Zhao pioooooooooip@gmail.com --- fs/smb/server/server.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c index 40420544c..15dd13e76 100644 --- a/fs/smb/server/server.c +++ b/fs/smb/server/server.c @@ -244,8 +244,14 @@ static void __handle_ksmbd_work(struct ksmbd_work *work, if (work->sess && work->sess->enc && work->encrypted && conn->ops->encrypt_resp) { rc = conn->ops->encrypt_resp(work); - if (rc < 0) + 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; + } + } } if (work->sess) ksmbd_user_session_put(work->sess);
On Tue, Nov 4, 2025 at 11:12 PM Qianchang Zhao pioooooooooip@gmail.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@gmail.com Reported-by: Zhitong Liu liuzhitong1993@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Qianchang Zhao pioooooooooip@gmail.com
fs/smb/server/server.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c index 40420544c..15dd13e76 100644 --- a/fs/smb/server/server.c +++ b/fs/smb/server/server.c @@ -244,8 +244,14 @@ static void __handle_ksmbd_work(struct ksmbd_work *work, if (work->sess && work->sess->enc && work->encrypted && conn->ops->encrypt_resp) { rc = conn->ops->encrypt_resp(work);
if (rc < 0)
if (rc < 0) { conn->ops->set_rsp_status(work, STATUS_DATA_ERROR);work->encrypted = false;if (work->tr_buf) {kvfree(work->tr_buf);
->tr_buf is freed in ksmbd_free_work_struct(). How can tr_buf not be freed? Thanks.
work->tr_buf = NULL;}} } if (work->sess) ksmbd_user_session_put(work->sess);-- 2.34.1
When encrypt_resp() fails in the send path, we set STATUS_DATA_ERROR but leave work->encrypted true. The send path then still assumes a valid transform buffer and tries to build/send an encrypted reply.
Clear work->encrypted on failure to force a plaintext error reply. The transform buffer (if allocated) is released by ksmbd_free_work_struct(), so no explicit kvfree(tr_buf) is needed.
Reported-by: Qianchang Zhao pioooooooooip@gmail.com Reported-by: Zhitong Liu liuzhitong1993@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Qianchang Zhao pioooooooooip@gmail.com
--- v2: - Drop explicit kvfree(tr_buf); it is freed in ksmbd_free_work_struct(). - Keep only 'work->encrypted = false' and update the commit message.
fs/smb/server/server.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c index 40420544c..a7444a78f 100644 --- a/fs/smb/server/server.c +++ b/fs/smb/server/server.c @@ -244,8 +244,10 @@ static void __handle_ksmbd_work(struct ksmbd_work *work, if (work->sess && work->sess->enc && work->encrypted && conn->ops->encrypt_resp) { rc = conn->ops->encrypt_resp(work); - if (rc < 0) + if (rc < 0) { conn->ops->set_rsp_status(work, STATUS_DATA_ERROR); + work->encrypted = false; + } } if (work->sess) ksmbd_user_session_put(work->sess);
On Thu, Nov 6, 2025 at 3:58 PM Qianchang Zhao pioooooooooip@gmail.com wrote:
When encrypt_resp() fails in the send path, we set STATUS_DATA_ERROR but leave work->encrypted true. The send path then still assumes a valid transform buffer and tries to build/send an encrypted reply.
Clear work->encrypted on failure to force a plaintext error reply.
ksmbd will send a plain text error reply regardless of the work->encrypted value. It doesn't seem to make any sense to set this to false. Thanks.
linux-stable-mirror@lists.linaro.org
-
Namjae Jeon -
Qianchang Zhao