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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,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 DA2A4C10F13 for ; Thu, 11 Apr 2019 11:46:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B25312133D for ; Thu, 11 Apr 2019 11:46:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726783AbfDKLql (ORCPT ); Thu, 11 Apr 2019 07:46:41 -0400 Received: from ozlabs.org ([203.11.71.1]:53819 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726137AbfDKLql (ORCPT ); Thu, 11 Apr 2019 07:46:41 -0400 Received: by ozlabs.org (Postfix, from userid 1034) id 44fzl33Dtjz9sCF; Thu, 11 Apr 2019 21:46:38 +1000 (AEST) From: Michael Ellerman To: stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: linuxppc-dev@ozlabs.org, diana.craciun@nxp.com, msuchanek@suse.de, christophe.leroy@c-s.fr Subject: [PATCH stable v4.9 04/35] powerpc: Avoid code patching freed init sections Date: Thu, 11 Apr 2019 21:45:59 +1000 Message-Id: <20190411114630.4042-5-mpe@ellerman.id.au> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190411114630.4042-1-mpe@ellerman.id.au> References: <20190411114630.4042-1-mpe@ellerman.id.au> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Michael Neuling commit 51c3c62b58b357e8d35e4cc32f7b4ec907426fe3 upstream. This stops us from doing code patching in init sections after they've been freed. In this chain: kvm_guest_init() -> kvm_use_magic_page() -> fault_in_pages_readable() -> __get_user() -> __get_user_nocheck() -> barrier_nospec(); We have a code patching location at barrier_nospec() and kvm_guest_init() is an init function. This whole chain gets inlined, so when we free the init section (hence kvm_guest_init()), this code goes away and hence should no longer be patched. We seen this as userspace memory corruption when using a memory checker while doing partition migration testing on powervm (this starts the code patching post migration via /sys/kernel/mobility/migration). In theory, it could also happen when using /sys/kernel/debug/powerpc/barrier_nospec. Cc: stable@vger.kernel.org # 4.13+ Signed-off-by: Michael Neuling Reviewed-by: Nicholas Piggin Reviewed-by: Christophe Leroy Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/setup.h | 1 + arch/powerpc/lib/code-patching.c | 8 ++++++++ arch/powerpc/mm/mem.c | 2 ++ 3 files changed, 11 insertions(+) diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h index 703ddf752516..709f4e739ae8 100644 --- a/arch/powerpc/include/asm/setup.h +++ b/arch/powerpc/include/asm/setup.h @@ -8,6 +8,7 @@ extern void ppc_printk_progress(char *s, unsigned short hex); extern unsigned int rtas_data; extern unsigned long long memory_limit; +extern bool init_mem_is_free; extern unsigned long klimit; extern void *zalloc_maybe_bootmem(size_t size, gfp_t mask); diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 753d591f1b52..c77c486fbf24 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -14,12 +14,20 @@ #include #include #include +#include +#include int patch_instruction(unsigned int *addr, unsigned int instr) { int err; + /* Make sure we aren't patching a freed init section */ + if (init_mem_is_free && init_section_contains(addr, 4)) { + pr_debug("Skipping init section patching addr: 0x%px\n", addr); + return 0; + } + __put_user_size(instr, addr, 4, err); if (err) return err; diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c index 5f844337de21..1e93dbc88e80 100644 --- a/arch/powerpc/mm/mem.c +++ b/arch/powerpc/mm/mem.c @@ -62,6 +62,7 @@ #endif unsigned long long memory_limit; +bool init_mem_is_free; #ifdef CONFIG_HIGHMEM pte_t *kmap_pte; @@ -396,6 +397,7 @@ void __init mem_init(void) void free_initmem(void) { ppc_md.progress = ppc_printk_progress; + init_mem_is_free = true; free_initmem_default(POISON_FREE_INITMEM); } -- 2.20.1