On Fri, 2016-12-23 at 17:58 -0800, Andy Lutomirski wrote:
On Fri, Dec 23, 2016 at 5:37 PM, Ricardo Neri ricardo.neri-calderon@linux.intel.com wrote:
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@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: 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 | 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;}Now that I've read the cover letter, I see what's going on. This should not warn -- user code can easily trigger this deliberately.
OK, I'll remove it. Are you concerned about the warning printing the calltrace, even only once?