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Subject[ 063/100] proc: Use nd_jump_link in proc_ns_follow_link
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3.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Eric W. Biederman" <ebiederm@xmission.com>

commit db04dc679bcc780ad6907943afe24a30de974a1b upstream.

Update proc_ns_follow_link to use nd_jump_link instead of just
manually updating nd.path.dentry.

This fixes the BUG_ON(nd->inode != parent->d_inode) reported by Dave
Jones and reproduced trivially with mkdir /proc/self/ns/uts/a.

Sigh it looks like the VFS change to require use of nd_jump_link
happend while proc_ns_follow_link was baking and since the common case
of proc_ns_follow_link continued to work without problems the need for
making this change was overlooked.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/proc/namespaces.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -118,7 +118,7 @@ static void *proc_ns_follow_link(struct
struct super_block *sb = inode->i_sb;
struct proc_inode *ei = PROC_I(inode);
struct task_struct *task;
- struct dentry *ns_dentry;
+ struct path ns_path;
void *error = ERR_PTR(-EACCES);

task = get_proc_task(inode);
@@ -128,14 +128,14 @@ static void *proc_ns_follow_link(struct
if (!ptrace_may_access(task, PTRACE_MODE_READ))
goto out_put_task;

- ns_dentry = proc_ns_get_dentry(sb, task, ei->ns_ops);
- if (IS_ERR(ns_dentry)) {
- error = ERR_CAST(ns_dentry);
+ ns_path.dentry = proc_ns_get_dentry(sb, task, ei->ns_ops);
+ if (IS_ERR(ns_path.dentry)) {
+ error = ERR_CAST(ns_path.dentry);
goto out_put_task;
}

- dput(nd->path.dentry);
- nd->path.dentry = ns_dentry;
+ ns_path.mnt = mntget(nd->path.mnt);
+ nd_jump_link(nd, &ns_path);
error = NULL;

out_put_task:



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