This is a note to let you know that I've just added the patch titled ksmbd: limit pdu length size according to connection status to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ksmbd-limit-pdu-length-size-according-to-connection-status.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 62c487b53a7ff31e322cf2874d3796b8202c54a5 Mon Sep 17 00:00:00 2001 From: Namjae Jeon <linkinjeon@xxxxxxxxxx> Date: Wed, 25 Jan 2023 00:13:20 +0900 Subject: ksmbd: limit pdu length size according to connection status From: Namjae Jeon <linkinjeon@xxxxxxxxxx> commit 62c487b53a7ff31e322cf2874d3796b8202c54a5 upstream. Stream protocol length will never be larger than 16KB until session setup. After session setup, the size of requests will not be larger than 16KB + SMB2 MAX WRITE size. This patch limits these invalidly oversized requests and closes the connection immediately. Fixes: 0626e6641f6b ("cifsd: add server handler for central processing and tranport layers") Cc: stable@xxxxxxxxxxxxxxx Reported-by: zdi-disclosures@xxxxxxxxxxxxxx # ZDI-CAN-18259 Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx> Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ksmbd/connection.c | 17 +++++++++++++++-- fs/ksmbd/smb2pdu.h | 5 +++-- 2 files changed, 18 insertions(+), 4 deletions(-) --- a/fs/ksmbd/connection.c +++ b/fs/ksmbd/connection.c @@ -280,7 +280,7 @@ int ksmbd_conn_handler_loop(void *p) { struct ksmbd_conn *conn = (struct ksmbd_conn *)p; struct ksmbd_transport *t = conn->transport; - unsigned int pdu_size; + unsigned int pdu_size, max_allowed_pdu_size; char hdr_buf[4] = {0,}; int size; @@ -305,13 +305,26 @@ int ksmbd_conn_handler_loop(void *p) pdu_size = get_rfc1002_len(hdr_buf); ksmbd_debug(CONN, "RFC1002 header %u bytes\n", pdu_size); + if (conn->status == KSMBD_SESS_GOOD) + max_allowed_pdu_size = + SMB3_MAX_MSGSIZE + conn->vals->max_write_size; + else + max_allowed_pdu_size = SMB3_MAX_MSGSIZE; + + if (pdu_size > max_allowed_pdu_size) { + pr_err_ratelimited("PDU length(%u) excceed maximum allowed pdu size(%u) on connection(%d)\n", + pdu_size, max_allowed_pdu_size, + conn->status); + break; + } + /* * Check if pdu size is valid (min : smb header size, * max : 0x00FFFFFF). */ if (pdu_size < __SMB2_HEADER_STRUCTURE_SIZE || pdu_size > MAX_STREAM_PROT_LEN) { - continue; + break; } /* 4 for rfc1002 length field */ --- a/fs/ksmbd/smb2pdu.h +++ b/fs/ksmbd/smb2pdu.h @@ -24,8 +24,9 @@ #define SMB21_DEFAULT_IOSIZE (1024 * 1024) #define SMB3_DEFAULT_TRANS_SIZE (1024 * 1024) -#define SMB3_MIN_IOSIZE (64 * 1024) -#define SMB3_MAX_IOSIZE (8 * 1024 * 1024) +#define SMB3_MIN_IOSIZE (64 * 1024) +#define SMB3_MAX_IOSIZE (8 * 1024 * 1024) +#define SMB3_MAX_MSGSIZE (4 * 4096) /* * Definitions for SMB2 Protocol Data Units (network frames) Patches currently in stable-queue which might be from linkinjeon@xxxxxxxxxx are queue-6.1/ksmbd-downgrade-ndr-version-error-message-to-debug.patch queue-6.1/ksmbd-limit-pdu-length-size-according-to-connection-status.patch queue-6.1/ksmbd-add-max-connections-parameter.patch queue-6.1/ksmbd-do-not-sign-response-to-session-request-for-guest-login.patch