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Date: Fri, 23 Dec 2016 17:37:40 -0800 From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com> To: Ingo Molnar <mingo@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...e.de>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org> Cc: linux-kernel@...r.kernel.org, x86@...nel.org, <linux-msdos@...r.kernel.org>, <wine-devel@...ehq.org>, Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>, Dave Hansen <dave.hansen@...ux.intel.com>, Adam Buchbinder <adam.buchbinder@...il.com>, Colin Ian King <colin.king@...onical.com>, Lorenzo Stoakes <lstoakes@...il.com>, Qiaowei Ren <qiaowei.ren@...el.com>, "Ravi V . Shankar" <ravi.v.shankar@...el.com> Subject: [v2 2/7] x86/mpx: Fail when implicit zero-displacement is used along with R/EBP Section 2.2.1.2 of the Intel 64 and IA-32 Architectures Software Developer's Manual volume 2A states that when memory addressing with no explicit displacement (i.e, mod part of ModR/M is 0), a SIB byte is used and the base of the SIB byte points to (R/EBP) (i.e., base = 5), an explicit displacement of 0 must be used. Make the address decoder to return -EINVAL in such a case. Cc: Dave Hansen <dave.hansen@...ux.intel.com> Cc: Adam Buchbinder <adam.buchbinder@...il.com> Cc: Colin Ian King <colin.king@...onical.com> Cc: Lorenzo Stoakes <lstoakes@...il.com> Cc: Qiaowei Ren <qiaowei.ren@...el.com> Cc: Ravi V. Shankar <ravi.v.shankar@...el.com> Cc: x86@...nel.org Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com> --- arch/x86/mm/mpx.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index 6a75a75..71681d0 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -120,6 +120,13 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs, case REG_TYPE_BASE: regno = X86_SIB_BASE(insn->sib.value); + if (regno == 5 && X86_MODRM_RM(insn->modrm.value) == 0) { + WARN_ONCE(1, "An explicit displacement is required when %sBP used as SIB base.", + (IS_ENABLED(CONFIG_X86_64) && insn->x86_64) ? + "R13 or R" : "E"); + return -EINVAL; + } + if (X86_REX_B(insn->rex_prefix.value)) regno += 8; break; -- 2.9.3
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