From 76ba89c76f2c74e208d93a9e7c698e39eeb3b85c Mon Sep 17 00:00:00 2001
From: Colin Ian King <colin.king@canonical.com>
Date: Mon, 4 Sep 2017 18:50:05 +0100
Subject: [PATCH] commoncap: move assignment of fs_ns to avoid null pointer
dereference
The pointer fs_ns is assigned from inode->i_ib->s_user_ns before
a null pointer check on inode, hence if inode is actually null we
will get a null pointer dereference on this assignment. Fix this
by only dereferencing inode after the null pointer check on
inode.
Detected by CoverityScan CID#1455328 ("Dereference before null check")
Fixes: 8db6c34f1dbc ("Introduce v3 namespaced file capabilities")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Cc: stable@vger.kernel.org
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
---
security/commoncap.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/security/commoncap.c b/security/commoncap.c
index c25e0d27537f8..fc46f5b852510 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -585,13 +585,14 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data
struct vfs_ns_cap_data data, *nscaps = &data;
struct vfs_cap_data *caps = (struct vfs_cap_data *) &data;
kuid_t rootkuid;
- struct user_namespace *fs_ns = inode->i_sb->s_user_ns;
+ struct user_namespace *fs_ns;
memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
if (!inode)
return -ENODATA;
+ fs_ns = inode->i_sb->s_user_ns;
size = __vfs_getxattr((struct dentry *)dentry, inode,
XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ);
if (size == -ENODATA || size == -EOPNOTSUPP)
--
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