Commit a7560a01 authored Dec 10, 2013 by Tejun Heo Committed by Greg Kroah-Hartman Dec 10, 2013

sysfs: fix use-after-free in sysfs_kill_sb()



While restructuring the [u]mount path, 4b93dc9b ("sysfs, kernfs:
prepare mount path for kernfs") incorrectly updated sysfs_kill_sb() so
that it first kills super_block and then tries to dereference its
namespace tag to drop it.  Fix it by caching namespace tag before
killing the superblock and then drop the cached namespace tag.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Tested-by: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/g/20131205031051.GC5135@yliu-dev.sh.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 9b2db6e1

fs/sysfs/mount.c

+3 −1

Original line number	Original line	Diff line number	Diff line
	@@ -45,8 +45,10 @@ static struct dentry sysfs_mount(struct file_system_type fs_type,

	static void sysfs_kill_sb(struct super_block *sb)		static void sysfs_kill_sb(struct super_block *sb)
	{		{
			void ns = (void )kernfs_super_ns(sb);

	kernfs_kill_sb(sb);		kernfs_kill_sb(sb);
	kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)kernfs_super_ns(sb));		kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
	}		}

	static struct file_system_type sysfs_fs_type = {		static struct file_system_type sysfs_fs_type = {