[PATCH] autofs: sanity check status reported with AUTOFS_DEV_IOCTL_FAIL

[NeilBrown]

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().

Signed-off-by: NeilBrown <neilb@xxxxxxxx>
---
 fs/autofs4/dev-ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index 734cbf8d9676..dd9f1bebb5a3 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -344,7 +344,7 @@ 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);
 }
 
-- 
2.12.2

Attachment: signature.asc
Description: PGP signature