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 21:56:27 +0200 |
| commit | 3b388f33a1fc643f5e9dc496c741eafdf6ebef49 (patch) | |
| tree | 3d1eaf04ea0951bfce4dbfcd5ca8f5465ffc014e | |
| parent | 10e30152633a23d3da2326ff23f4b0b5fc1e94ce (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>
| -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 f7c4393f8535..036c21246d6a 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1542,7 +1542,8 @@ static inline int walk_component(struct nameidata *nd, struct path *path, if (should_follow_link(inode, 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; } @@ -2824,7 +2825,8 @@ finish_lookup: if (should_follow_link(inode, !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; } |