From 606035e76e79b14bf7a7c219140c045a952cc76e Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 14 Sep 2013 17:32:12 -0400 Subject: 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 Acked-by: Ian Kent --- fs/autofs4/waitq.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) (limited to 'fs/autofs4') 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); } /* -- cgit v1.2.3-70-g09d2