Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752431AbdGPOkr (ORCPT ); Sun, 16 Jul 2017 10:40:47 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:44258 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751962AbdGPON4 (ORCPT ); Sun, 16 Jul 2017 10:13:56 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Thomas Gleixner" , "Borislav Petkov" , "Ingo Molnar" , "Masami Hiramatsu" , "Peter Zijlstra" , "Linus Torvalds" Date: Sun, 16 Jul 2017 14:56:46 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 004/178] kprobes/x86: Fix kernel panic when certain exception-handling addresses are probed In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3049 Lines: 85 3.16.46-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Masami Hiramatsu commit 75013fb16f8484898eaa8d0b08fed942d790f029 upstream. Fix to the exception table entry check by using probed address instead of the address of copied instruction. This bug may cause unexpected kernel panic if user probe an address where an exception can happen which should be fixup by __ex_table (e.g. copy_from_user.) Unless user puts a kprobe on such address, this doesn't cause any problem. This bug has been introduced years ago, by commit: 464846888d9a ("x86/kprobes: Fix a bug which can modify kernel code permanently"). Signed-off-by: Masami Hiramatsu Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 464846888d9a ("x86/kprobes: Fix a bug which can modify kernel code permanently") Link: http://lkml.kernel.org/r/148829899399.28855.12581062400757221722.stgit@devbox Signed-off-by: Ingo Molnar Signed-off-by: Ben Hutchings --- arch/x86/kernel/kprobes/common.h | 2 +- arch/x86/kernel/kprobes/core.c | 6 +++--- arch/x86/kernel/kprobes/opt.c | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-) --- a/arch/x86/kernel/kprobes/common.h +++ b/arch/x86/kernel/kprobes/common.h @@ -67,7 +67,7 @@ #endif /* Ensure if the instruction can be boostable */ -extern int can_boost(kprobe_opcode_t *instruction); +extern int can_boost(kprobe_opcode_t *instruction, void *addr); /* Recover instruction if given address is probed */ extern unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr); --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -163,12 +163,12 @@ NOKPROBE_SYMBOL(skip_prefixes); * Returns non-zero if opcode is boostable. * RIP relative instructions are adjusted at copying time in 64 bits mode */ -int can_boost(kprobe_opcode_t *opcodes) +int can_boost(kprobe_opcode_t *opcodes, void *addr) { kprobe_opcode_t opcode; kprobe_opcode_t *orig_opcodes = opcodes; - if (search_exception_tables((unsigned long)opcodes)) + if (search_exception_tables((unsigned long)addr)) return 0; /* Page fault may occur on this address. */ retry: @@ -385,7 +385,7 @@ static int arch_copy_kprobe(struct kprob * __copy_instruction can modify the displacement of the instruction, * but it doesn't affect boostable check. */ - if (can_boost(p->ainsn.insn)) + if (can_boost(p->ainsn.insn, p->addr)) p->ainsn.boostable = 0; else p->ainsn.boostable = -1; --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -177,7 +177,7 @@ static int copy_optimized_instructions(u while (len < RELATIVEJUMP_SIZE) { ret = __copy_instruction(dest + len, src + len); - if (!ret || !can_boost(dest + len)) + if (!ret || !can_boost(dest + len, src + len)) return -EINVAL; len += ret; }