From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934638AbeEIKnW (ORCPT ); Wed, 9 May 2018 06:43:22 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:59627 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932570AbeEIKnU (ORCPT ); Wed, 9 May 2018 06:43:20 -0400 To: bhe@redhat.com, ying.huang@intel.com, hpa@zytor.com, mingo@elte.hu Cc: syzbot+d96f60296ef613fe1d69@syzkaller.appspotmail.com, kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, akpm@linux-foundation.org, dyoung@redhat.com, mingo@redhat.com, prudo@linux.vnet.ibm.com, takahiro.akashi@linaro.org, tglx@linutronix.de, thomas.lendacky@amd.com, x86@kernel.org Subject: [PATCH v3] x86/kexec: avoid double free_page() upon do_kexec_load() failure. From: Tetsuo Handa References: <0000000000005dbad8056b20cabc@google.com> <20180503232922.GE30581@MiWiFi-R3L-srv> <201805082026.CAD35992.LFMQtSVFFOOJOH@I-love.SAKURA.ne.jp> In-Reply-To: <201805082026.CAD35992.LFMQtSVFFOOJOH@I-love.SAKURA.ne.jp> Message-Id: <201805091942.DGG12448.tMFVFSJFQOOLHO@I-love.SAKURA.ne.jp> X-Mailer: Winbiff [Version 2.51 PL2] X-Accept-Language: ja,en,zh Date: Wed, 9 May 2018 19:42:20 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>From ff82bedd3e12f0d3353282054ae48c3bd8c72012 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Wed, 9 May 2018 12:12:39 +0900 Subject: [PATCH v3] x86/kexec: avoid double free_page() upon do_kexec_load() failure. syzbot is reporting crashes after memory allocation failure inside do_kexec_load() [1]. This is because free_transition_pgtable() is called by both init_transition_pgtable() and machine_kexec_cleanup() when memory allocation failed inside init_transition_pgtable(). Regarding 32bit code, machine_kexec_free_page_tables() is called by both machine_kexec_alloc_page_tables() and machine_kexec_cleanup() when memory allocation failed inside machine_kexec_alloc_page_tables(). Fix this by leaving the error handling to machine_kexec_cleanup() (and optionally setting NULL after free_page()). [1] https://syzkaller.appspot.com/bug?id=91e52396168cf2bdd572fe1e1bc0bc645c1c6b40 Signed-off-by: Tetsuo Handa Reported-by: syzbot Fixes: f5deb79679af6eb4 ("x86: kexec: Use one page table in x86_64 machine_kexec") Fixes: 92be3d6bdf2cb349 ("kexec/i386: allocate page table pages dynamically") Cc: Huang Ying Cc: H. Peter Anvin Cc: Ingo Molnar --- arch/x86/kernel/machine_kexec_32.c | 6 +++++- arch/x86/kernel/machine_kexec_64.c | 5 ++++- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c index 60cdec6..d1ab07e 100644 --- a/arch/x86/kernel/machine_kexec_32.c +++ b/arch/x86/kernel/machine_kexec_32.c @@ -57,12 +57,17 @@ static void load_segments(void) static void machine_kexec_free_page_tables(struct kimage *image) { free_page((unsigned long)image->arch.pgd); + image->arch.pgd = NULL; #ifdef CONFIG_X86_PAE free_page((unsigned long)image->arch.pmd0); + image->arch.pmd0 = NULL; free_page((unsigned long)image->arch.pmd1); + image->arch.pmd1 = NULL; #endif free_page((unsigned long)image->arch.pte0); + image->arch.pte0 = NULL; free_page((unsigned long)image->arch.pte1); + image->arch.pte1 = NULL; } static int machine_kexec_alloc_page_tables(struct kimage *image) @@ -79,7 +84,6 @@ static int machine_kexec_alloc_page_tables(struct kimage *image) !image->arch.pmd0 || !image->arch.pmd1 || #endif !image->arch.pte0 || !image->arch.pte1) { - machine_kexec_free_page_tables(image); return -ENOMEM; } return 0; diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index a5e55d8..6010449 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -39,9 +39,13 @@ static void free_transition_pgtable(struct kimage *image) { free_page((unsigned long)image->arch.p4d); + image->arch.p4d = NULL; free_page((unsigned long)image->arch.pud); + image->arch.pud = NULL; free_page((unsigned long)image->arch.pmd); + image->arch.pmd = NULL; free_page((unsigned long)image->arch.pte); + image->arch.pte = NULL; } static int init_transition_pgtable(struct kimage *image, pgd_t *pgd) @@ -91,7 +95,6 @@ static int init_transition_pgtable(struct kimage *image, pgd_t *pgd) set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC_NOENC)); return 0; err: - free_transition_pgtable(image); return result; } -- 1.8.3.1