From patchwork Sat Aug 31 03:10:24 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 11124743 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 067611399 for ; Sat, 31 Aug 2019 03:11:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D8F0123777 for ; Sat, 31 Aug 2019 03:11:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567221102; bh=GJ3U4px7b3ANezBJVEhyma8S78tvLyrPWzysEmmy8a8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0d4UJlbZeqYsN7rZLTHMMjdYi9pB9waY7V4SjZZ1iWkvDVDgILt3WL4FJFKOWv4zK KzEjamvJtXFS1ZSZzmoSvjS/qaDiNFAWVgD+gDQf7+5XhrmvVjdj4mKjZcQjb2Epru ops7/mHMjm0Kem8c2eevHFeNkprsMwPA71VyizYo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728410AbfHaDLi (ORCPT ); Fri, 30 Aug 2019 23:11:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:60972 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728246AbfHaDLi (ORCPT ); Fri, 30 Aug 2019 23:11:38 -0400 Received: from zzz.tds (h184-61-154-48.mdsnwi.dsl.dynamic.tds.net [184.61.154.48]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8315423697; Sat, 31 Aug 2019 03:11:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567221097; bh=GJ3U4px7b3ANezBJVEhyma8S78tvLyrPWzysEmmy8a8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Abk8lRoXiqwTnfyyX/UusjkVXFbidWi8kHdGOtAfHi3Xd4gW9wMLQV9Y2nA1LhsC3 K+27ju15Hl2PVbaUVOM9zrR6+p1AO0C83A+pSeFXOXUpBJl3yT/D4m1gQRRtK9F8mK KIZwPE+U5Ojvw0H8KUgaRICLEa7MECts6Z2peNYw= From: Eric Biggers To: Alexander Viro , linux-fsdevel@vger.kernel.org Cc: syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org, syzbot+5aca688dac0796c56129@syzkaller.appspotmail.com, David Howells Subject: [PATCH vfs/for-next] vfs: fix vfs_get_single_reconf_super error handling Date: Fri, 30 Aug 2019 22:10:24 -0500 Message-Id: <20190831031024.26008-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <0000000000003675ae05915a9fd3@google.com> References: <0000000000003675ae05915a9fd3@google.com> MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Eric Biggers syzbot reported an invalid free in debugfs_release_dentry(). The reproducer tries to mount debugfs with the 'dirsync' option, which is not allowed. The bug is that if reconfigure_super() fails in vfs_get_super(), deactivate_locked_super() is called, but also fs_context::root is left non-NULL which causes deactivate_super() to be called again later. Fix it by releasing fs_context::root in the error path. Reported-by: syzbot+5aca688dac0796c56129@syzkaller.appspotmail.com Fixes: e478b48498a7 ("vfs: Add a single-or-reconfig keying to vfs_get_super()") Cc: David Howells Signed-off-by: Eric Biggers --- fs/super.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/super.c b/fs/super.c index 0f913376fc4c..99195e15be05 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1194,8 +1194,11 @@ int vfs_get_super(struct fs_context *fc, fc->root = dget(sb->s_root); if (keying == vfs_get_single_reconf_super) { err = reconfigure_super(fc); - if (err < 0) + if (err < 0) { + dput(fc->root); + fc->root = NULL; goto error; + } } }