diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2013-09-14 17:32:12 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2013-09-16 19:16:38 -0400 |
| commit | 606035e76e79b14bf7a7c219140c045a952cc76e (patch) | |
| tree | 43958ffa5278f8ba9d1d6a8884087b196952e94a | |
| parent | 3711d86a2de17e967b576af8b8a1e9351a7d1466 (diff) | |
autofs4: close the races around autofs4_notify_daemon()
Don't drop ->wq_mutex before calling autofs4_notify_daemon() only to regain it
there. Besides being pointless, that opens a race window where autofs4_wait_release()
could've come and freed wq->name.name. And do the debugging printk in the "reused an
existing wq" case before dropping ->wq_mutex - the same reason...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Ian Kent <raven@themaw.net>
| -rw-r--r-- | fs/autofs4/waitq.c | 13 |
1 files changed, 3 insertions, 10 deletions
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c index 3db70dae40d..689e40d983a 100644 --- a/fs/autofs4/waitq.c +++ b/fs/autofs4/waitq.c @@ -109,13 +109,7 @@ static void autofs4_notify_daemon(struct autofs_sb_info *sbi, pkt.hdr.proto_version = sbi->version; pkt.hdr.type = type; - mutex_lock(&sbi->wq_mutex); - /* Check if we have become catatonic */ - if (sbi->catatonic) { - mutex_unlock(&sbi->wq_mutex); - return; - } switch (type) { /* Kernel protocol v4 missing and expire packets */ case autofs_ptype_missing: @@ -427,7 +421,6 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry, wq->tgid = current->tgid; wq->status = -EINTR; /* Status return if interrupted */ wq->wait_ctr = 2; - mutex_unlock(&sbi->wq_mutex); if (sbi->version < 5) { if (notify == NFY_MOUNT) @@ -449,15 +442,15 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry, (unsigned long) wq->wait_queue_token, wq->name.len, wq->name.name, notify); - /* autofs4_notify_daemon() may block */ + /* autofs4_notify_daemon() may block; it will unlock ->wq_mutex */ autofs4_notify_daemon(sbi, wq, type); } else { wq->wait_ctr++; - mutex_unlock(&sbi->wq_mutex); - kfree(qstr.name); DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d", (unsigned long) wq->wait_queue_token, wq->name.len, wq->name.name, notify); + mutex_unlock(&sbi->wq_mutex); + kfree(qstr.name); } /* |