From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Brian Gerst <brgerst@gmail.com>,
Chris Metcalf <cmetcalf@mellanox.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Liang Z Li <liang.z.li@intel.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Huang Rui <ray.huang@amd.com>, Jiri Slaby <jslaby@suse.cz>,
Jonathan Corbet <corbet@lwn.net>,
"Michael S. Tsirkin" <mst@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Vlastimil Babka <vbabka@suse.cz>, Chen Yucong <slaoub@gmail.com>,
Alexandre Julliard <julliard@winehq.org>,
Stas Sergeev <stsp@list.ru>, Fenghua Yu <fenghua.yu@intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Shuah Khan <shuah@kernel.org>,
linux-kernel@vger.kernel.org, x86@kernel.org,
linux-msdos@vger.kernel.org, wine-devel@winehq.org,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
Adam Buchbinder <adam.buchbinder@gmail.com>,
Colin Ian King <colin.king@canonical.com>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Qiaowei Ren <qiaowei.ren@intel.com>,
Nathan Howard <liverlint@gmail.com>,
Adan Hawthorn <adanhawthorn@gmail.com>,
Joe Perches <joe@perches.com>
Subject: [v6 PATCH 03/21] x86/mpx: Do not use R/EBP as base in the SIB byte with Mod = 0
Date: Tue, 7 Mar 2017 16:32:36 -0800 [thread overview]
Message-ID: <20170308003254.27833-4-ricardo.neri-calderon@linux.intel.com> (raw)
In-Reply-To: <20170308003254.27833-1-ricardo.neri-calderon@linux.intel.com>
Section 2.2.1.2 of the Intel 64 and IA-32 Architectures Software
Developer's Manual volume 2A states that when a SIB byte is used and the
base of the SIB byte points to R/EBP (i.e., base = 5) and the mod part
of the ModRM byte is zero, the value of such register will not be used
as part of the address computation. To signal this, a -EDOM error is
returned to indicate callers that they should ignore the value.
Also, for this particular case, a displacement of 32-bits should follow
the SIB byte if the mod part of ModRM is equal to zero. The instruction
decoder ensures that this is the case.
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Nathan Howard <liverlint@gmail.com>
Cc: Adan Hawthorn <adanhawthorn@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: x86@kernel.org
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
---
arch/x86/mm/mpx.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index d9e92d6..ef7eb67 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -121,6 +121,17 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
case REG_TYPE_BASE:
regno = X86_SIB_BASE(insn->sib.value);
+ /*
+ * If mod is 0 and register R/EBP (regno=5) is indicated in the
+ * base part of the SIB byte, the value of such register should
+ * not be used in the address computation. Also, a 32-bit
+ * displacement is expected in this case; the instruction
+ * decoder takes care of it. This is true for both R13 and
+ * R/EBP as REX.B will not be decoded.
+ */
+ if (regno == 5 && X86_MODRM_MOD(insn->modrm.value) == 0)
+ return -EDOM;
+
if (X86_REX_B(insn->rex_prefix.value))
regno += 8;
break;
@@ -161,16 +172,21 @@ static void __user *mpx_get_addr_ref(struct insn *insn, struct pt_regs *regs)
eff_addr = regs_get_register(regs, addr_offset);
} else {
if (insn->sib.nbytes) {
+ /*
+ * Negative values in the base and index offset means
+ * an error when decoding the SIB byte. Except -EDOM,
+ * which means that the registers should not be used
+ * in the address computation.
+ */
base_offset = get_reg_offset(insn, regs, REG_TYPE_BASE);
- if (base_offset < 0)
+ if (unlikely(base_offset == -EDOM))
+ base = 0;
+ else if (unlikely(base_offset < 0))
goto out_err;
+ else
+ base = regs_get_register(regs, base_offset);
indx_offset = get_reg_offset(insn, regs, REG_TYPE_INDEX);
- /*
- * A negative offset generally means a error, except
- * -EDOM, which means that the contents of the register
- * should not be used as index.
- */
if (unlikely(indx_offset == -EDOM))
indx = 0;
else if (unlikely(indx_offset < 0))
@@ -178,7 +194,6 @@ static void __user *mpx_get_addr_ref(struct insn *insn, struct pt_regs *regs)
else
indx = regs_get_register(regs, indx_offset);
- base = regs_get_register(regs, base_offset);
eff_addr = base + indx * (1 << X86_SIB_SCALE(sib));
} else {
addr_offset = get_reg_offset(insn, regs, REG_TYPE_RM);
--
2.9.3
next prev parent reply other threads:[~2017-03-08 0:37 UTC|newest]
Thread overview: 112+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-08 0:32 [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 01/21] x86/mpx: Use signed variables to compute effective addresses Ricardo Neri
2017-04-11 21:56 ` Borislav Petkov
2017-04-26 1:40 ` Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 02/21] x86/mpx: Do not use SIB index if index points to R/ESP Ricardo Neri
2017-04-11 11:31 ` Borislav Petkov
2017-04-26 1:39 ` Ricardo Neri
2017-03-08 0:32 ` Ricardo Neri [this message]
2017-04-11 22:08 ` [v6 PATCH 03/21] x86/mpx: Do not use R/EBP as base in the SIB byte with Mod = 0 Borislav Petkov
2017-04-26 2:04 ` Ricardo Neri
2017-04-26 8:05 ` Borislav Petkov
2017-04-27 22:49 ` Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 04/21] x86/mpx, x86/insn: Relocate insn util functions to a new insn-kernel Ricardo Neri
2017-04-12 10:03 ` Borislav Petkov
2017-04-26 2:05 ` Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 05/21] x86/insn-eval: Add utility functions to get register offsets Ricardo Neri
2017-04-12 16:28 ` Borislav Petkov
2017-04-26 18:13 ` Ricardo Neri
2017-04-28 10:40 ` Borislav Petkov
2017-03-08 0:32 ` [v6 PATCH 06/21] x86/insn-eval: Add utility functions to get segment selector Ricardo Neri
2017-04-18 9:42 ` Borislav Petkov
2017-04-26 20:44 ` Ricardo Neri
2017-04-26 20:47 ` Ricardo Neri
2017-04-30 17:15 ` Borislav Petkov
2017-05-05 18:31 ` Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 07/21] x86/insn-eval: Add utility function to get segment descriptor Ricardo Neri
2017-04-19 10:26 ` Borislav Petkov
2017-04-26 21:51 ` Ricardo Neri
2017-05-04 11:02 ` Borislav Petkov
2017-05-12 2:13 ` Ricardo Neri
2017-05-15 17:27 ` Borislav Petkov
2017-03-08 0:32 ` [v6 PATCH 08/21] x86/insn-eval: Add utility function to get segment descriptor base address Ricardo Neri
2017-04-20 8:25 ` Borislav Petkov
2017-04-26 22:37 ` Ricardo Neri
2017-05-05 17:19 ` Borislav Petkov
2017-05-12 2:09 ` Ricardo Neri
2017-04-26 22:52 ` Ricardo Neri
2017-05-05 17:28 ` Borislav Petkov
2017-05-12 2:06 ` Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 09/21] x86/insn-eval: Add functions to get default operand and address sizes Ricardo Neri
2017-04-20 13:06 ` Borislav Petkov
2017-04-27 1:07 ` Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 10/21] x86/insn-eval: Do not use R/EBP as base if mod in ModRM is zero Ricardo Neri
2017-04-21 10:52 ` Borislav Petkov
2017-04-27 1:29 ` Ricardo Neri
2017-05-07 17:20 ` Borislav Petkov
2017-05-12 1:57 ` Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 11/21] insn/eval: Incorporate segment base in address computation Ricardo Neri
2017-04-21 14:55 ` Borislav Petkov
2017-04-27 1:31 ` Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 12/21] x86/insn: Support both signed 32-bit and 64-bit effective addresses Ricardo Neri
2017-04-25 13:51 ` Borislav Petkov
2017-04-27 3:33 ` Ricardo Neri
2017-05-08 11:42 ` Borislav Petkov
2017-05-12 1:55 ` Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 13/21] x86/insn-eval: Add support to resolve 16-bit addressing encodings Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 14/21] x86/insn-eval: Add wrapper function for 16-bit and 32-bit address encodings Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 15/21] x86/mm: Relocate page fault error codes to traps.h Ricardo Neri
2017-03-08 16:08 ` Andy Lutomirski
2017-03-08 0:32 ` [v6 PATCH 16/21] x86/cpufeature: Add User-Mode Instruction Prevention definitions Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 17/21] x86: Add emulation code for UMIP instructions Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 18/21] x86/umip: Force a page fault when unable to copy emulated result to user Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 19/21] x86/traps: Fixup general protection faults caused by UMIP Ricardo Neri
2017-03-08 15:54 ` Andy Lutomirski
2017-03-08 0:32 ` [v6 PATCH 20/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri
2017-03-08 0:32 ` [v6 PATCH 21/21] selftests/x86: Add tests for " Ricardo Neri
2017-03-08 15:56 ` Andy Lutomirski
2017-03-10 23:38 ` Ricardo Neri
2017-03-08 14:08 ` [v6 PATCH 00/21] x86: Enable " Stas Sergeev
2017-03-08 16:06 ` Andy Lutomirski
2017-03-08 16:29 ` Stas Sergeev
2017-03-08 16:46 ` Andy Lutomirski
2017-03-08 16:53 ` Stas Sergeev
2017-03-09 1:11 ` Ricardo Neri
2017-03-09 22:05 ` Stas Sergeev
2017-03-10 2:41 ` Andy Lutomirski
2017-03-10 10:30 ` Stas Sergeev
2017-03-10 21:04 ` Andy Lutomirski
2017-03-10 21:37 ` Stas Sergeev
2017-03-09 1:15 ` Ricardo Neri
2017-03-09 22:10 ` Stas Sergeev
2017-03-10 2:39 ` Andy Lutomirski
2017-03-10 11:33 ` Stas Sergeev
2017-03-10 14:17 ` Andy Lutomirski
2017-03-11 1:22 ` Ricardo Neri
2017-03-10 23:59 ` Ricardo Neri
2017-03-13 21:25 ` Stas Sergeev
2017-03-27 23:46 ` Ricardo Neri
2017-03-28 9:38 ` Stas Sergeev
2017-03-29 4:38 ` Ricardo Neri
2017-03-29 20:55 ` Stas Sergeev
2017-03-30 5:14 ` Ricardo Neri
2017-03-30 10:10 ` Stas Sergeev
2017-03-31 1:33 ` Ricardo Neri
2017-03-31 14:11 ` Alexandre Julliard
2017-03-31 21:26 ` Stas Sergeev
2017-04-01 2:18 ` Andy Lutomirski
2017-04-04 2:02 ` Ricardo Neri
2017-04-04 6:08 ` Alexandre Julliard
2017-04-01 13:08 ` Stas Sergeev
2017-04-01 17:49 ` H. Peter Anvin
2017-04-02 15:52 ` Andy Lutomirski
2017-04-04 9:59 ` Stas Sergeev
2017-04-04 2:05 ` Ricardo Neri
2017-04-04 8:03 ` Stas Sergeev
2017-03-10 23:58 ` Ricardo Neri
2017-03-09 0:46 ` Ricardo Neri
2017-03-09 22:01 ` Stas Sergeev
2017-03-10 23:47 ` Ricardo Neri
2017-03-10 23:58 ` Stas Sergeev
2017-03-11 0:13 ` Ricardo Neri
2017-03-08 16:07 ` Andy Lutomirski
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