From: Namjae Jeon <linkinjeon@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Reported-by: Chih-Yen Chang <cc85nod@xxxxxxxxx>
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 | 12 ++++++++++++
1 file changed, 12 insertions(+)
--- a/fs/ksmbd/connection.c
+++ b/fs/ksmbd/connection.c
@@ -296,6 +296,9 @@ 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
@@ -352,6 +355,9 @@ 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;
@@ -379,6 +385,12 @@ 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;
