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authorAl Viro <viro@zeniv.linux.org.uk>2013-09-14 17:32:12 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2013-09-16 19:16:38 -0400
commit606035e76e79b14bf7a7c219140c045a952cc76e (patch)
tree43958ffa5278f8ba9d1d6a8884087b196952e94a
parent3711d86a2de17e967b576af8b8a1e9351a7d1466 (diff)
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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.c13
1 files changed, 3 insertions, 10 deletions
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 3db70dae40d3..689e40d983ad 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);
}
/*