From: Namjae Jeon linkinjeon@kernel.org
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@vger.kernel.org Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-18259 Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -274,7 +274,7 @@ 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;
@@ -299,13 +299,26 @@ 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 @@ -113,8 +113,9 @@ #define SMB21_DEFAULT_IOSIZE (1024 * 1024) #define SMB3_DEFAULT_IOSIZE (4 * 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)
/* * SMB2 Header Definition