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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12EF8C433DF for ; Fri, 5 Jun 2020 14:16:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E03C920C56 for ; Fri, 5 Jun 2020 14:16:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591366580; bh=k4MdHdKkOwBPSJvJDuxl0DBhK1L0mnYClje06rnuBRo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=qlFC1WFqg6+nphVOcwnQTHv8n6JA3KDn6K5kqR31GcXPjxDcwhsrOdWshxBdHYUG6 viYA6bsFpQJF45auQ9gILqvjF4wDPSls6IN1CdWkvFOYB9TAFW7mbsipeaQb3f96mn sI0MARQk/QpCq4x76c68SgyySaxMTzAL3fRG3sWk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728216AbgFEOQU (ORCPT ); Fri, 5 Jun 2020 10:16:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:45268 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728188AbgFEOQO (ORCPT ); Fri, 5 Jun 2020 10:16:14 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 41D302075B; Fri, 5 Jun 2020 14:16:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591366573; bh=k4MdHdKkOwBPSJvJDuxl0DBhK1L0mnYClje06rnuBRo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GISaba2yYy+uWtO1XsJO0sS+xu/UFvbkEI5avR8fG0wSzyzgwTUmxh60HPvxP9jEo 47eQWaMjIQNyEtTOw1CwoFVdfbzq64HRBj+yM2/80WMOefb8tVsJrj4tNHcGkhaWrR JkUDOhczztG54NqjCmRyeT5oUeN6nq1TtKgVKQhQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+1e925b4b836afe85a1c6@syzkaller-ppc64.appspotmail.com, syzbot+587b2421926808309d21@syzkaller-ppc64.appspotmail.com, syzbot+58320b7171734bf79d26@syzkaller.appspotmail.com, syzbot+d6074fb08bdb2e010520@syzkaller.appspotmail.com, Daniel Axtens , Andrew Morton , Michael Ellerman , Andrew Donnellan , David Rientjes , Akash Goel , Guenter Roeck , Salvatore Bonaccorso , Linus Torvalds Subject: [PATCH 5.7 09/14] kernel/relay.c: handle alloc_percpu returning NULL in relay_open Date: Fri, 5 Jun 2020 16:14:59 +0200 Message-Id: <20200605135951.572445358@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200605135951.018731965@linuxfoundation.org> References: <20200605135951.018731965@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Axtens commit 54e200ab40fc14c863bcc80a51e20b7906608fce upstream. alloc_percpu() may return NULL, which means chan->buf may be set to NULL. In that case, when we do *per_cpu_ptr(chan->buf, ...), we dereference an invalid pointer: BUG: Unable to handle kernel data access at 0x7dae0000 Faulting instruction address: 0xc0000000003f3fec ... NIP relay_open+0x29c/0x600 LR relay_open+0x270/0x600 Call Trace: relay_open+0x264/0x600 (unreliable) __blk_trace_setup+0x254/0x600 blk_trace_setup+0x68/0xa0 sg_ioctl+0x7bc/0x2e80 do_vfs_ioctl+0x13c/0x1300 ksys_ioctl+0x94/0x130 sys_ioctl+0x48/0xb0 system_call+0x5c/0x68 Check if alloc_percpu returns NULL. This was found by syzkaller both on x86 and powerpc, and the reproducer it found on powerpc is capable of hitting the issue as an unprivileged user. Fixes: 017c59c042d0 ("relay: Use per CPU constructs for the relay channel buffer pointers") Reported-by: syzbot+1e925b4b836afe85a1c6@syzkaller-ppc64.appspotmail.com Reported-by: syzbot+587b2421926808309d21@syzkaller-ppc64.appspotmail.com Reported-by: syzbot+58320b7171734bf79d26@syzkaller.appspotmail.com Reported-by: syzbot+d6074fb08bdb2e010520@syzkaller.appspotmail.com Signed-off-by: Daniel Axtens Signed-off-by: Andrew Morton Reviewed-by: Michael Ellerman Reviewed-by: Andrew Donnellan Acked-by: David Rientjes Cc: Akash Goel Cc: Andrew Donnellan Cc: Guenter Roeck Cc: Salvatore Bonaccorso Cc: [4.10+] Link: http://lkml.kernel.org/r/20191219121256.26480-1-dja@axtens.net Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/relay.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/kernel/relay.c +++ b/kernel/relay.c @@ -581,6 +581,11 @@ struct rchan *relay_open(const char *bas return NULL; chan->buf = alloc_percpu(struct rchan_buf *); + if (!chan->buf) { + kfree(chan); + return NULL; + } + chan->version = RELAYFS_CHANNEL_VERSION; chan->n_subbufs = n_subbufs; chan->subbuf_size = subbuf_size;