diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2015-04-24 15:47:07 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-05-06 21:59:20 +0200 |
| commit | 7507c7e11351c4dde218f1bc8bc9fce98329a5fa (patch) | |
| tree | 63b1d1946404f0c9c49dfac29b514858b0cc8697 /fs | |
| parent | 07308f3a46406daa58f3ec44f00022538c2e3e23 (diff) | |
RCU pathwalk breakage when running into a symlink overmounting something
commit 3cab989afd8d8d1bc3d99fef0e7ed87c31e7b647 upstream.
Calling unlazy_walk() in walk_component() and do_last() when we find
a symlink that needs to be followed doesn't acquire a reference to vfsmount.
That's fine when the symlink is on the same vfsmount as the parent directory
(which is almost always the case), but it's not always true - one _can_
manage to bind a symlink on top of something. And in such cases we end up
with excessive mntput().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/namei.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/namei.c b/fs/namei.c index 0dd72c8e65fd..ccb8000f3459 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1545,7 +1545,8 @@ static inline int walk_component(struct nameidata *nd, struct path *path, if (should_follow_link(path->dentry, follow)) { if (nd->flags & LOOKUP_RCU) { - if (unlikely(unlazy_walk(nd, path->dentry))) { + if (unlikely(nd->path.mnt != path->mnt || + unlazy_walk(nd, path->dentry))) { err = -ECHILD; goto out_err; } @@ -2992,7 +2993,8 @@ finish_lookup: if (should_follow_link(path->dentry, !symlink_ok)) { if (nd->flags & LOOKUP_RCU) { - if (unlikely(unlazy_walk(nd, path->dentry))) { + if (unlikely(nd->path.mnt != path->mnt || + unlazy_walk(nd, path->dentry))) { error = -ECHILD; goto out; } |