From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5493CC4167D for ; Tue, 10 May 2022 13:24:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243204AbiEJN2s (ORCPT ); Tue, 10 May 2022 09:28:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243246AbiEJN0j (ORCPT ); Tue, 10 May 2022 09:26:39 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1BAC72317D5; Tue, 10 May 2022 06:19:13 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id F070661665; Tue, 10 May 2022 13:19:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0984DC385C2; Tue, 10 May 2022 13:19:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1652188752; bh=7QJDgg4sfkmypf0Qd7Xo9nYtMAuC3p7KgxsYAL5z3QI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eFWStOnhkuznbzJ7SfP5P2BDM+i4qKRLp13n4IcZMEVW60LzQaKh6Le0tDF25lXj5 9T8q6apHiYZYoBGvj92HlSQl8kplq/nAk35ehMSvslJEzrm0ioyj3gePc7NtAAJDkz snNA3ewKZe/NLYORXs67RWl9dD29NgMbnxxH5kN4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ying Xu , Xin Long , Marcelo Ricardo Leitner , "David S. Miller" , Sasha Levin Subject: [PATCH 4.19 33/88] sctp: check asoc strreset_chunk in sctp_generate_reconf_event Date: Tue, 10 May 2022 15:07:18 +0200 Message-Id: <20220510130734.707839964@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220510130733.735278074@linuxfoundation.org> References: <20220510130733.735278074@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xin Long [ Upstream commit 165e3e17fe8fe6a8aab319bc6e631a2e23b9a857 ] A null pointer reference issue can be triggered when the response of a stream reconf request arrives after the timer is triggered, such as: send Incoming SSN Reset Request ---> CPU0: reconf timer is triggered, go to the handler code before hold sk lock <--- reply with Outgoing SSN Reset Request CPU1: process Outgoing SSN Reset Request, and set asoc->strreset_chunk to NULL CPU0: continue the handler code, hold sk lock, and try to hold asoc->strreset_chunk, crash! In Ying Xu's testing, the call trace is: [ ] BUG: kernel NULL pointer dereference, address: 0000000000000010 [ ] RIP: 0010:sctp_chunk_hold+0xe/0x40 [sctp] [ ] Call Trace: [ ] [ ] sctp_sf_send_reconf+0x2c/0x100 [sctp] [ ] sctp_do_sm+0xa4/0x220 [sctp] [ ] sctp_generate_reconf_event+0xbd/0xe0 [sctp] [ ] call_timer_fn+0x26/0x130 This patch is to fix it by returning from the timer handler if asoc strreset_chunk is already set to NULL. Fixes: 7b9438de0cd4 ("sctp: add stream reconf timer") Reported-by: Ying Xu Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/sctp/sm_sideeffect.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c index 2a94240eac36..82d96441e64d 100644 --- a/net/sctp/sm_sideeffect.c +++ b/net/sctp/sm_sideeffect.c @@ -473,6 +473,10 @@ void sctp_generate_reconf_event(struct timer_list *t) goto out_unlock; } + /* This happens when the response arrives after the timer is triggered. */ + if (!asoc->strreset_chunk) + goto out_unlock; + error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT, SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_RECONF), asoc->state, asoc->ep, asoc, -- 2.35.1