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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 5C862C04E53 for ; Wed, 15 May 2019 11:46:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2BFD72089E for ; Wed, 15 May 2019 11:46:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557920784; bh=EA6NedQph8PMX3qsnEJopeDYubZLnPwmefdEEmbJ5RY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MDTFzdfBoiEJb9bOThFQkt5k7V2UcC5M88PgEfW3n4EPejeMHMOuKP6wXwCbfrZw/ LvOduwh3PZ+PTHlX41kG1F/hBe2fnxw2Wu21k19zs3nhJxT33IwBroAJB0gYL92rTp X7mZwwSjV5WSADyNpG1jLmPg9RTC6Gkx84fBSY5g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732120AbfEOLqW (ORCPT ); Wed, 15 May 2019 07:46:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:36196 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731995AbfEOLZZ (ORCPT ); Wed, 15 May 2019 07:25:25 -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 CCB812084F; Wed, 15 May 2019 11:25:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557919525; bh=EA6NedQph8PMX3qsnEJopeDYubZLnPwmefdEEmbJ5RY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P2m/3vszLu1F1BTj0CtRo8Dny7Yct94igUq97KSK6xOKWo0RzcmTqXkssW6xWtGxG ZrXi2RGqwabCPlGNQmF9iNB40abPSNOeOmBc+eddgkRpGgN6gDaCZJgQvIINwoIP1g 2C3XeiJFBsIKv5H7shFgBGBK4m//y2h+fHEKQZV8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rick Lindsley , Michael Ellerman Subject: [PATCH 4.19 108/113] powerpc/book3s/64: check for NULL pointer in pgd_alloc() Date: Wed, 15 May 2019 12:56:39 +0200 Message-Id: <20190515090701.876183332@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190515090652.640988966@linuxfoundation.org> References: <20190515090652.640988966@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: Rick Lindsley commit f39356261c265a0689d7ee568132d516e8b6cecc upstream. When the memset code was added to pgd_alloc(), it failed to consider that kmem_cache_alloc() can return NULL. It's uncommon, but not impossible under heavy memory contention. Example oops: Unable to handle kernel paging request for data at address 0x00000000 Faulting instruction address: 0xc0000000000a4000 Oops: Kernel access of bad area, sig: 11 [#1] LE SMP NR_CPUS=2048 NUMA pSeries CPU: 70 PID: 48471 Comm: entrypoint.sh Kdump: loaded Not tainted 4.14.0-115.6.1.el7a.ppc64le #1 task: c000000334a00000 task.stack: c000000331c00000 NIP: c0000000000a4000 LR: c00000000012f43c CTR: 0000000000000020 REGS: c000000331c039c0 TRAP: 0300 Not tainted (4.14.0-115.6.1.el7a.ppc64le) MSR: 800000010280b033 CR: 44022840 XER: 20040000 CFAR: c000000000008874 DAR: 0000000000000000 DSISR: 42000000 SOFTE: 1 ... NIP [c0000000000a4000] memset+0x68/0x104 LR [c00000000012f43c] mm_init+0x27c/0x2f0 Call Trace: mm_init+0x260/0x2f0 (unreliable) copy_mm+0x11c/0x638 copy_process.isra.28.part.29+0x6fc/0x1080 _do_fork+0xdc/0x4c0 ppc_clone+0x8/0xc Instruction dump: 409e000c b0860000 38c60002 409d000c 90860000 38c60004 78a0d183 78a506a0 7c0903a6 41820034 60000000 60420000 f8860008 f8860010 f8860018 Fixes: fc5c2f4a55a2 ("powerpc/mm/hash64: Zero PGD pages on allocation") Cc: stable@vger.kernel.org # v4.16+ Signed-off-by: Rick Lindsley Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/include/asm/book3s/64/pgalloc.h | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/powerpc/include/asm/book3s/64/pgalloc.h +++ b/arch/powerpc/include/asm/book3s/64/pgalloc.h @@ -83,6 +83,9 @@ static inline pgd_t *pgd_alloc(struct mm pgd = kmem_cache_alloc(PGT_CACHE(PGD_INDEX_SIZE), pgtable_gfp_flags(mm, GFP_KERNEL)); + if (unlikely(!pgd)) + return pgd; + /* * Don't scan the PGD for pointers, it contains references to PUDs but * those references are not full pointers and so can't be recognised by