From: NeilBrown <neilb@suse.com>
Date: Fri, 23 Jun 2017 22:08:43 +0000 (-0700)
Subject: autofs: sanity check status reported with AUTOFS_DEV_IOCTL_FAIL
X-Git-Tag: v3.2.93~14
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c5a12b60e20e19b4accf10371e94c520eab3d459;p=pandora-kernel.git

autofs: sanity check status reported with AUTOFS_DEV_IOCTL_FAIL

commit 9fa4eb8e490a28de40964b1b0e583d8db4c7e57c upstream.

If a positive status is passed with the AUTOFS_DEV_IOCTL_FAIL ioctl,
autofs4_d_automount() will return

   ERR_PTR(status)

with that status to follow_automount(), which will then dereference an
invalid pointer.

So treat a positive status the same as zero, and map to ENOENT.

See comment in systemd src/core/automount.c::automount_send_ready().

Link: http://lkml.kernel.org/r/871sqwczx5.fsf@notabene.neil.brown.name
Signed-off-by: NeilBrown <neilb@suse.com>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index 62d7a6d9a701..38a2f2c512d7 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -345,7 +345,7 @@ static int autofs_dev_ioctl_fail(struct file *fp,
 	int status;
 
 	token = (autofs_wqt_t) param->fail.token;
-	status = param->fail.status ? param->fail.status : -ENOENT;
+	status = param->fail.status < 0 ? param->fail.status : -ENOENT;
 	return autofs4_wait_release(sbi, token, status);
 }