Messages in this thread Patch in this message | | | From | (Eric W. Biederman) | Date | Sat, 09 Mar 2013 00:28:27 -0800 | Subject | Re: BUG_ON(nd->inode != parent->d_inode); |
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Dave Jones <davej@redhat.com> writes:
> On Fri, Mar 08, 2013 at 07:38:33PM -0800, Eric W. Biederman wrote: > > Dave Jones <davej@redhat.com> writes: > > > > > On Fri, Mar 08, 2013 at 07:16:09PM -0800, Linus Torvalds wrote: > > > > Goodie. Your bug reports gave me heartburn. But it sounds like we have an > > > > angle on all of the ones you've seen now? > > > > > > > > Or have I forgotten about some case? > > > > > > To be honest I've lost track of the whole collection. > > > Let me repull your latest tree, and see what falls out. > > > (I'll turn off CONFIG_USER_NS for now too until that gets fixed) > > > > It was CONFIG_UTS_NS that tripped you. > > > > Since I can trigger this with /proc/self/ns/mnt/a you are going to be > > able to compile this one out. > > fwiw, the other namespace procfs files look like they have the same bug > > I just triggered it again on /proc/571/task/571/ns/net
Yep same code.
I will do a proper submission of this after I have slept. But here is the fix.
From: "Eric W. Biederman" <ebiederm@xmission.com> Date: Sat, 9 Mar 2013 00:14:45 -0800 Subject: [PATCH] proc: Use nd_jump_link in proc_ns_follow_link
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.
Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> --- fs/proc/namespaces.c | 12 ++++++------ 1 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index b7a4719..66b51c0 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -118,7 +118,7 @@ static void *proc_ns_follow_link(struct dentry *dentry, struct nameidata *nd) 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 dentry *dentry, struct nameidata *nd) 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: -- 1.7.5.4
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