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authorAl Viro <viro@zeniv.linux.org.uk>2015-04-24 15:47:07 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-05-06 21:56:27 +0200
commit3b388f33a1fc643f5e9dc496c741eafdf6ebef49 (patch)
tree3d1eaf04ea0951bfce4dbfcd5ca8f5465ffc014e /fs
parent10e30152633a23d3da2326ff23f4b0b5fc1e94ce (diff)
downloadlinux-linaro-stable-3b388f33a1fc643f5e9dc496c741eafdf6ebef49.tar.gz
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.c6
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;
}