From: Yao Liu <yotta.liu@ucloud.cn>
Date: Mon, 28 Jan 2019 11:44:14 +0000 (+0800)
Subject: nfs: Fix NULL pointer dereference of dev_name
X-Git-Tag: v5.15~6990^2~4
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=80ff00172407e0aad4b10b94ef0816fc3e7813cb;p=platform%2Fkernel%2Flinux-starfive.git

nfs: Fix NULL pointer dereference of dev_name

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>
---

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 22ce3c8..0570391 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1895,6 +1895,11 @@ 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, ']');