1 From d12b3cc31f2a54269de92803aa0df38871b09f83 Mon Sep 17 00:00:00 2001
2 From: Yao Liu <yotta.liu@ucloud.cn>
3 Date: Mon, 28 Jan 2019 19:47:28 +0800
4 Subject: cifs: Fix NULL pointer dereference of devname
6 [ Upstream commit 68e2672f8fbd1e04982b8d2798dd318bf2515dd2 ]
8 There is a NULL pointer dereference of devname in strspn()
10 The oops looks something like:
12 CIFS: Attempting to mount (null)
13 BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
15 RIP: 0010:strspn+0x0/0x50
18 ? cifs_parse_mount_options+0x222/0x1710 [cifs]
19 ? cifs_get_volume_info+0x2f/0x80 [cifs]
20 cifs_setup_volume_info+0x20/0x190 [cifs]
21 cifs_get_volume_info+0x50/0x80 [cifs]
22 cifs_smb3_do_mount+0x59/0x630 [cifs]
23 ? ida_alloc_range+0x34b/0x3d0
24 cifs_do_mount+0x11/0x20 [cifs]
26 vfs_kern_mount+0x6b/0x170
29 __x64_sys_mount+0x25/0x30
30 do_syscall_64+0x65/0x220
31 entry_SYSCALL_64_after_hwframe+0x49/0xbe
33 Fix this by adding a NULL check on devname in cifs_parse_devname()
35 Signed-off-by: Yao Liu <yotta.liu@ucloud.cn>
36 Signed-off-by: Steve French <stfrench@microsoft.com>
37 Signed-off-by: Sasha Levin <sashal@kernel.org>
39 fs/cifs/connect.c | 5 +++++
40 1 file changed, 5 insertions(+)
42 diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
43 index eacf57c24ca9..9cb72fd40eff 100644
44 --- a/fs/cifs/connect.c
45 +++ b/fs/cifs/connect.c
46 @@ -1255,6 +1255,11 @@ cifs_parse_devname(const char *devname, struct smb_vol *vol)
47 const char *delims = "/\\";
50 + if (unlikely(!devname || !*devname)) {
51 + cifs_dbg(VFS, "Device name not specified.\n");
55 /* make sure we have a valid UNC double delimiter prefix */
56 len = strspn(devname, delims);