From: Ian Kent <ikent@redhat.com> Date: Tue, 12 Aug 2008 12:27:20 +0800 Subject: [autofs4] fix waitq locking Message-id: 20080812042719.15842.92775.stgit@web.messagingengine.com O-Subject: [RHEL 5.3 PATCH 11/20] autofs4 - fix waitq locking [Realted: bz452139] Bugzilla: 452139 This patch is an upstream bug fix and shoud be associated with bug 452139. The autofs4_catatonic_mode() function accesses the wait queue without any locking but can be called at any time. This could lead to a possible double free of the name field of the wait and a double fput of the daemon communication pipe or an fput of a NULL file pointer. Signed-off-by: Ian Kent <raven@themaw.net> diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c index 99e6255..0873aed 100644 --- a/fs/autofs4/inode.c +++ b/fs/autofs4/inode.c @@ -163,8 +163,8 @@ void autofs4_kill_sb(struct super_block *sb) if (!sbi) goto out_kill_sb; - if (!sbi->catatonic) - autofs4_catatonic_mode(sbi); /* Free wait queues, close pipe */ + /* Free wait queues, close pipe */ + autofs4_catatonic_mode(sbi); /* Clean up and release dangling references */ autofs4_force_release(sbi); diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c index f0ad52b..5103f3d 100644 --- a/fs/autofs4/waitq.c +++ b/fs/autofs4/waitq.c @@ -28,6 +28,12 @@ void autofs4_catatonic_mode(struct autofs_sb_info *sbi) { struct autofs_wait_queue *wq, *nwq; + mutex_lock(&sbi->wq_mutex); + if (sbi->catatonic) { + mutex_unlock(&sbi->wq_mutex); + return; + } + DPRINTK("entering catatonic mode"); sbi->catatonic = 1; @@ -45,6 +51,8 @@ void autofs4_catatonic_mode(struct autofs_sb_info *sbi) } fput(sbi->pipe); /* Close the pipe */ sbi->pipe = NULL; + sbi->pipefd = -1; + mutex_unlock(&sbi->wq_mutex); } static int autofs4_write(struct file *file, const void *addr, int bytes) @@ -390,17 +398,10 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry, wq->name.name, notify); } - /* wq->name is NULL if and only if the lock is already released */ - - if (sbi->catatonic) { - /* We might have slept, so check again for catatonic mode */ - wq->status = -ENOENT; - if (wq->name.name) { - kfree(wq->name.name); - wq->name.name = NULL; - } - } - + /* + * wq->name.name is NULL iff the lock is already released + * or the mount has been made catatonic. + */ if (wq->name.name) { /* Block all but "shutdown" signals while waiting */ sigset_t oldset;