linux-kernel - [tip:x86/urgent] objtool: Fix '-mtune=atom' decoding support in objtool 2.0

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <tip-deecd4d71b12626db48544faa66bb897e2cafd07@git.kernel.org>
Date:   Mon, 21 Aug 2017 07:10:25 -0700
From:   tip-bot for Josh Poimboeuf <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     torvalds@...ux-foundation.org, jpoimboe@...hat.com,
        tglx@...utronix.de, linux-kernel@...r.kernel.org, hpa@...or.com,
        mingo@...nel.org, peterz@...radead.org, arnd@...db.de
Subject: [tip:x86/urgent] objtool: Fix '-mtune=atom' decoding support in
 objtool 2.0

Commit-ID:  deecd4d71b12626db48544faa66bb897e2cafd07
Gitweb:     http://git.kernel.org/tip/deecd4d71b12626db48544faa66bb897e2cafd07
Author:     Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Thu, 27 Jul 2017 15:56:55 -0500
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 21 Aug 2017 16:07:27 +0200

objtool: Fix '-mtune=atom' decoding support in objtool 2.0

With '-mtune=atom', which is enabled with CONFIG_MATOM=y, GCC uses some
unusual instructions for setting up the stack.

Instead of:

  mov %rsp, %rbp

it does:

  lea (%rsp), %rbp

And instead of:

  add imm, %rsp

it does:

  lea disp(%rsp), %rsp

Add support for these instructions to the objtool decoder.

Reported-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Fixes: baa41469a7b9 ("objtool: Implement stack validation 2.0")
Link: http://lkml.kernel.org/r/4ea1db896e821226efe1f8e09f270771bde47e65.1501188854.git.jpoimboe@redhat.com
[ This is a cherry-picked version of upcoming commit 5b8de48e82ba. ]
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 tools/objtool/arch/x86/decode.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index a36c2eb..4559a21a 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -271,7 +271,7 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
 	case 0x8d:
 		if (rex == 0x48 && modrm == 0x65) {
 
-			/* lea -disp(%rbp), %rsp */
+			/* lea disp(%rbp), %rsp */
 			*type = INSN_STACK;
 			op->src.type = OP_SRC_ADD;
 			op->src.reg = CFI_BP;
@@ -281,6 +281,30 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
 			break;
 		}
 
+		if (rex == 0x48 && (modrm == 0xa4 || modrm == 0x64) &&
+		    sib == 0x24) {
+
+			/* lea disp(%rsp), %rsp */
+			*type = INSN_STACK;
+			op->src.type = OP_SRC_ADD;
+			op->src.reg = CFI_SP;
+			op->src.offset = insn.displacement.value;
+			op->dest.type = OP_DEST_REG;
+			op->dest.reg = CFI_SP;
+			break;
+		}
+
+		if (rex == 0x48 && modrm == 0x2c && sib == 0x24) {
+
+			/* lea (%rsp), %rbp */
+			*type = INSN_STACK;
+			op->src.type = OP_SRC_REG;
+			op->src.reg = CFI_SP;
+			op->dest.type = OP_DEST_REG;
+			op->dest.reg = CFI_BP;
+			break;
+		}
+
 		if (rex == 0x4c && modrm == 0x54 && sib == 0x24 &&
 		    insn.displacement.value == 8) {