From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:39964 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405332AbeKTD00 (ORCPT ); Mon, 19 Nov 2018 22:26:26 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+4e975615ca01f2277bdd@syzkaller.appspotmail.com, Kirill Tkhai , Miklos Szeredi Subject: [PATCH 4.4 108/160] fuse: Fix use-after-free in fuse_dev_do_read() Date: Mon, 19 Nov 2018 17:29:07 +0100 Message-Id: <20181119162641.315405113@linuxfoundation.org> In-Reply-To: <20181119162630.031306128@linuxfoundation.org> References: <20181119162630.031306128@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kirill Tkhai commit bc78abbd55dd28e2287ec6d6502b842321a17c87 upstream. We may pick freed req in this way: [cpu0] [cpu1] fuse_dev_do_read() fuse_dev_do_write() list_move_tail(&req->list, ...); ... spin_unlock(&fpq->lock); ... ... request_end(fc, req); ... fuse_put_request(fc, req); if (test_bit(FR_INTERRUPTED, ...)) queue_interrupt(fiq, req); Fix that by keeping req alive until we finish all manipulations. Reported-by: syzbot+4e975615ca01f2277bdd@syzkaller.appspotmail.com Signed-off-by: Kirill Tkhai Signed-off-by: Miklos Szeredi Fixes: 46c34a348b0a ("fuse: no fc->lock for pqueue parts") Cc: # v4.2 Signed-off-by: Greg Kroah-Hartman --- fs/fuse/dev.c | 2 ++ 1 file changed, 2 insertions(+) --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -1328,12 +1328,14 @@ static ssize_t fuse_dev_do_read(struct f goto out_end; } list_move_tail(&req->list, &fpq->processing); + __fuse_get_request(req); spin_unlock(&fpq->lock); set_bit(FR_SENT, &req->flags); /* matches barrier in request_wait_answer() */ smp_mb__after_atomic(); if (test_bit(FR_INTERRUPTED, &req->flags)) queue_interrupt(fiq, req); + fuse_put_request(fc, req); return reqsize;