From: Namjae Jeon linkinjeon@kernel.org
commit 368ba06881c395f1c9a7ba22203cf8d78b4addc0 upstream.
The length field of netbios header must be greater than the SMB header sizes(smb1 or smb2 header), otherwise the packet is an invalid SMB packet.
If `pdu_size` is 0, ksmbd allocates a 4 bytes chunk to `conn->request_buf`. In the function `get_smb2_cmd_val` ksmbd will read cmd from `rcv_hdr->Command`, which is `conn->request_buf + 12`, causing the KASAN detector to print the following error message:
[ 7.205018] BUG: KASAN: slab-out-of-bounds in get_smb2_cmd_val+0x45/0x60 [ 7.205423] Read of size 2 at addr ffff8880062d8b50 by task ksmbd:42632/248 ... [ 7.207125] <TASK> [ 7.209191] get_smb2_cmd_val+0x45/0x60 [ 7.209426] ksmbd_conn_enqueue_request+0x3a/0x100 [ 7.209712] ksmbd_server_process_request+0x72/0x160 [ 7.210295] ksmbd_conn_handler_loop+0x30c/0x550 [ 7.212280] kthread+0x160/0x190 [ 7.212762] ret_from_fork+0x1f/0x30 [ 7.212981] </TASK>
Cc: stable@vger.kernel.org Reported-by: Chih-Yen Chang cc85nod@gmail.com 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 | 12 ++++++++++++ 1 file changed, 12 insertions(+)
--- a/fs/ksmbd/connection.c +++ b/fs/ksmbd/connection.c @@ -294,6 +294,9 @@ bool ksmbd_conn_alive(struct ksmbd_conn return true; }
+#define SMB1_MIN_SUPPORTED_HEADER_SIZE (sizeof(struct smb_hdr)) +#define SMB2_MIN_SUPPORTED_HEADER_SIZE (sizeof(struct smb2_hdr) + 4) + /** * ksmbd_conn_handler_loop() - session thread to listen on new smb requests * @p: connection instance @@ -350,6 +353,9 @@ int ksmbd_conn_handler_loop(void *p) if (pdu_size > MAX_STREAM_PROT_LEN) break;
+ if (pdu_size < SMB1_MIN_SUPPORTED_HEADER_SIZE) + break; + /* 4 for rfc1002 length field */ /* 1 for implied bcc[0] */ size = pdu_size + 4 + 1; @@ -377,6 +383,12 @@ int ksmbd_conn_handler_loop(void *p) continue; }
+ if (((struct smb2_hdr *)smb2_get_msg(conn->request_buf))->ProtocolId == + SMB2_PROTO_NUMBER) { + if (pdu_size < SMB2_MIN_SUPPORTED_HEADER_SIZE) + break; + } + if (!default_conn_ops.process_fn) { pr_err("No connection request callback\n"); break;