From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753112AbdC2FEz (ORCPT ); Wed, 29 Mar 2017 01:04:55 -0400 Received: from mail.kernel.org ([198.145.29.136]:42734 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752482AbdC2FEx (ORCPT ); Wed, 29 Mar 2017 01:04:53 -0400 From: Masami Hiramatsu To: linux-kernel@vger.kernel.org, Ingo Molnar Cc: Peter Zijlstra , Thomas Gleixner , "H . Peter Anvin" , Ananth N Mavinakayanahalli , Anil S Keshavamurthy , "David S . Miller" , Andrey Ryabinin , Ye Xiaolong , mhiramat@kernel.org Subject: [RFC PATCH tip/master V3 7/8] kprobes/x86: Use probe_kernel_read instead of memcpy Date: Wed, 29 Mar 2017 14:03:56 +0900 Message-Id: <149076382624.22469.10091613887942958518.stgit@devbox> X-Mailer: git-send-email 2.9.3 In-Reply-To: <149076333370.22469.11135086121721120819.stgit@devbox> References: <149076333370.22469.11135086121721120819.stgit@devbox> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use probe_kernel_read() for avoiding unexpected faults while copying kernel text in __recover_probed_insn(), __recover_optprobed_insn() and __copy_instruction(). Signed-off-by: Masami Hiramatsu --- Note that this is just an update patch which I had been sent to LKML last month ( https://lkml.org/lkml/2017/2/27/294 ) --- arch/x86/kernel/kprobes/core.c | 12 +++++++++--- arch/x86/kernel/kprobes/opt.c | 5 ++++- 2 files changed, 13 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 0dc24e6..722f544 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -259,7 +259,10 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) * Fortunately, we know that the original code is the ideal 5-byte * long NOP. */ - memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + if (probe_kernel_read(buf, (void *)addr, + MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) + return 0UL; + if (faddr) memcpy(buf, ideal_nops[NOP_ATOMIC5], 5); else @@ -271,7 +274,7 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) * Recover the probed instruction at addr for further analysis. * Caller must lock kprobes by kprobe_mutex, or disable preemption * for preventing to release referencing kprobes. - * Returns zero if the instruction can not get recovered. + * Returns zero if the instruction can not get recovered (or access failed). */ unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) { @@ -365,7 +368,10 @@ int __copy_instruction(u8 *dest, u8 *src) /* Another subsystem puts a breakpoint, failed to recover */ if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) return 0; - memcpy(dest, insn.kaddr, length); + + /* This can access kernel text if given address is not recovered */ + if (kernel_probe_read(dest, insn.kaddr, length)) + return 0; #ifdef CONFIG_X86_64 /* Only x86_64 has RIP relative instructions */ diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index b121037..5b52334 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -65,7 +65,10 @@ unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr) * overwritten by jump destination address. In this case, original * bytes must be recovered from op->optinsn.copied_insn buffer. */ - memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + if (probe_kernel_read(buf, (void *)addr, + MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) + return 0UL; + if (addr == (unsigned long)kp->addr) { buf[0] = kp->opcode; memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);