Commit 76ba89c7 authored Sep 04, 2017 by Colin Ian King Committed by James Morris Oct 19, 2017

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: 8db6c34f ("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>

parent 494b9ae7

security/commoncap.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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)