[PATCH 4.9 52/96] nfs: Fix NULL pointer dereference of dev_name

Greg Kroah-Hartman
2019-03-12T17:26:31Z

[ Upstream commit 80ff00172407e0aad4b10b94ef0816fc3e7813cb ]

There is a NULL pointer dereference of dev_name in nfs_parse_devname()

The oops looks something like:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
...
RIP: 0010:nfs_fs_mount+0x3b6/0xc20 [nfs]
...
Call Trace:
? ida_alloc_range+0x34b/0x3d0
? nfs_clone_super+0x80/0x80 [nfs]
? nfs_free_parsed_mount_data+0x60/0x60 [nfs]
mount_fs+0x52/0x170
? __init_waitqueue_head+0x3b/0x50
vfs_kern_mount+0x6b/0x170
do_mount+0x216/0xdc0
ksys_mount+0x83/0xd0
__x64_sys_mount+0x25/0x30
do_syscall_64+0x65/0x220
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fix this by adding a NULL check on dev_name

Signed-off-by: Yao Liu <yotta.liu@ucloud.cn>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfs/super.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 35aef192a13f..659ad12e33ba 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1904,6 +1904,11 @@ static int nfs_parse_devname(const char *dev_name,
size_t len;
char *end;

+ if (unlikely(!dev_name || !*dev_name)) {
+ dfprintk(MOUNT, "NFS: device name not specified\n");
+ return -EINVAL;
+ }
+
/* Is the host name protected with square brakcets? */
if (*dev_name == '[') {
end = strchr(++dev_name, ']');
--
2.19.1