From 5a11d4d0ee1ff284271f7265929d07ea4a1168a6 Mon Sep 17 00:00:00 2001 From: Ian Kent Date: Wed, 23 Jul 2008 21:30:17 -0700 Subject: autofs4: fix waitq locking 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/autofs4/inode.c | 4 ++-- fs/autofs4/waitq.c | 23 ++++++++++++----------- 2 files changed, 14 insertions(+), 13 deletions(-) (limited to 'fs') diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c index e3e7099..7bb3e5b 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 5208cfb..55aac10 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) @@ -333,17 +341,10 @@ 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; -- cgit v1.1