[PATCH 4.19 160/205] fuse: fix leaked notify reply

Greg Kroah-Hartman
2018-11-19T16:37:13Z

From: Miklos Szeredi <mszeredi@redhat.com>

commit 7fabaf303458fcabb694999d6fa772cc13d4e217 upstream.

fuse_request_send_notify_reply() may fail if the connection was reset for
some reason (e.g. fs was unmounted). Don't leak request reference in this
case. Besides leaking memory, this resulted in fc->num_waiting not being
decremented and hence fuse_wait_aborted() left in a hanging and unkillable
state.

Fixes: 2d45ba381a74 ("fuse: add retrieve request")
Fixes: b8f95e5d13f5 ("fuse: umount should wait for all requests")
Reported-and-tested-by: syzbot+6339eda9cb4ebbc4c37b@syzkaller.appspotmail.com
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> #v2.6.36
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/fuse/dev.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1724,8 +1724,10 @@ static int fuse_retrieve(struct fuse_con
req->in.args[1].size = total_len;

err = fuse_request_send_notify_reply(fc, req, outarg->notify_unique);
- if (err)
+ if (err) {
fuse_retrieve_end(fc, req);
+ fuse_put_request(fc, req);
+ }

return err;
}