From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 1/1] net: Fix use after free in the recvmmsg exit path Date: Mon, 14 Mar 2016 12:42:19 -0400 (EDT) Message-ID: <20160314.124219.1956200224905019589.davem@davemloft.net> References: <1457960195-4302-1-git-send-email-acme@kernel.org> <1457960195-4302-2-git-send-email-acme@kernel.org> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, acme@redhat.com, glider@google.com, edumazet@google.com, kcc@google.com, sasha.levin@oracle.com To: acme@kernel.org Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:47312 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751336AbcCNQmW (ORCPT ); Mon, 14 Mar 2016 12:42:22 -0400 In-Reply-To: <1457960195-4302-2-git-send-email-acme@kernel.org> Sender: netdev-owner@vger.kernel.org List-ID: From: Arnaldo Carvalho de Melo Date: Mon, 14 Mar 2016 09:56:35 -0300 > From: Arnaldo Carvalho de Melo > > The syzkaller fuzzer hit the following use-after-free: > > Call Trace: > [] __asan_report_load8_noabort+0x3e/0x40 mm/kasan/report.c:295 > [] __sys_recvmmsg+0x6fa/0x7f0 net/socket.c:2261 > [< inline >] SYSC_recvmmsg net/socket.c:2281 > [] SyS_recvmmsg+0x16f/0x180 net/socket.c:2270 > [] entry_SYSCALL_64_fastpath+0x16/0x7a > arch/x86/entry/entry_64.S:185 > > And, as Dmitry rightly assessed, that is because we can drop the > reference and then touch it when the underlying recvmsg calls return > some packets and then hit an error, which will make recvmmsg to set > sock->sk->sk_err, oops, fix it. > > Reported-and-Tested-by: Dmitry Vyukov > Cc: Alexander Potapenko > Cc: Eric Dumazet > Cc: Kostya Serebryany > Cc: Sasha Levin > Fixes: a2e2725541fa ("net: Introduce recvmmsg socket syscall") > http://lkml.kernel.org/r/20160122211644.GC2470@redhat.com > Signed-off-by: Arnaldo Carvalho de Melo Applied and queued up for -stable, thanks Arnaldo!