This is a note to let you know that I've just added the patch titled
don't bugger nd->seq on set_root_rcu() from follow_dotdot_rcu()
to the 3.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
don-t-bugger-nd-seq-on-set_root_rcu-from-follow_dotdot_rcu.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7bd88377d482e1eae3c5329b12e33cfd664fa6a9 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sat, 13 Sep 2014 21:55:46 -0400
Subject: don't bugger nd->seq on set_root_rcu() from follow_dotdot_rcu()
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
commit 7bd88377d482e1eae3c5329b12e33cfd664fa6a9 upstream.
return the value instead, and have path_init() do the assignment. Broken by
"vfs: Fix absolute RCU path walk failures due to uninitialized seq number",
which was Cc-stable with 2.6.38+ as destination. This one should go where
it went.
To avoid dummy value returned in case when root is already set (it would do
no harm, actually, since the only caller that doesn't ignore the return value
is guaranteed to have nd->root *not* set, but it's more obvious that way),
lift the check into callers. And do the same to set_root(), to keep them
in sync.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/namei.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -644,24 +644,22 @@ static int complete_walk(struct nameidat
static __always_inline void set_root(struct nameidata *nd)
{
- if (!nd->root.mnt)
- get_fs_root(current->fs, &nd->root);
+ get_fs_root(current->fs, &nd->root);
}
static int link_path_walk(const char *, struct nameidata *);
-static __always_inline void set_root_rcu(struct nameidata *nd)
+static __always_inline unsigned set_root_rcu(struct nameidata *nd)
{
- if (!nd->root.mnt) {
- struct fs_struct *fs = current->fs;
- unsigned seq;
+ struct fs_struct *fs = current->fs;
+ unsigned seq, res;
- do {
- seq = read_seqcount_begin(&fs->seq);
- nd->root = fs->root;
- nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
- } while (read_seqcount_retry(&fs->seq, seq));
- }
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->root = fs->root;
+ res = __read_seqcount_begin(&nd->root.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+ return res;
}
static void path_put_conditional(struct path *path, struct nameidata *nd)
@@ -861,7 +859,8 @@ follow_link(struct path *link, struct na
return PTR_ERR(s);
}
if (*s == '/') {
- set_root(nd);
+ if (!nd->root.mnt)
+ set_root(nd);
path_put(&nd->path);
nd->path = nd->root;
path_get(&nd->root);
@@ -1136,7 +1135,8 @@ static bool __follow_mount_rcu(struct na
static int follow_dotdot_rcu(struct nameidata *nd)
{
- set_root_rcu(nd);
+ if (!nd->root.mnt)
+ set_root_rcu(nd);
while (1) {
if (nd->path.dentry == nd->root.dentry &&
@@ -1249,7 +1249,8 @@ static void follow_mount(struct path *pa
static void follow_dotdot(struct nameidata *nd)
{
- set_root(nd);
+ if (!nd->root.mnt)
+ set_root(nd);
while(1) {
struct dentry *old = nd->path.dentry;
@@ -1847,7 +1848,7 @@ static int path_init(int dfd, const char
if (*name=='/') {
if (flags & LOOKUP_RCU) {
rcu_read_lock();
- set_root_rcu(nd);
+ nd->seq = set_root_rcu(nd);
} else {
set_root(nd);
path_get(&nd->root);
Patches currently in stable-queue which might be from viro@xxxxxxxxxxxxxxxxxx are
queue-3.16/fs-notify-don-t-show-f_handle-if-exportfs_encode_inode_fh-failed.patch
queue-3.16/ufs-fix-deadlocks-introduced-by-sb-mutex-merge.patch
queue-3.16/don-t-bugger-nd-seq-on-set_root_rcu-from-follow_dotdot_rcu.patch
queue-3.16/fsnotify-fdinfo-use-named-constants-instead-of-hardcoded-values.patch
queue-3.16/lockdep-revert-lockdep-check-in-raw_seqcount_begin.patch
queue-3.16/shmem-fix-nlink-for-rename-overwrite-directory.patch
queue-3.16/eventpoll-fix-uninitialized-variable-in-epoll_ctl.patch
queue-3.16/gfs2-fix-d_splice_alias-misuses.patch
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