diff options
| -rw-r--r-- | arch/x86/mm/mpx.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index 2ad1d4a42fcc..581a960a4f09 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -123,6 +123,14 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs, case REG_TYPE_BASE: regno = X86_SIB_BASE(insn->sib.value); + /* + * If ModRM.mod is 0 and SIB.base == 5, the base of the + * register-indirect addressing is 0. In this case, a + * 32-bit displacement follows the SIB byte. + */ + if (!X86_MODRM_MOD(insn->modrm.value) && regno == 5) + return -EDOM; + if (X86_REX_B(insn->rex_prefix.value)) regno += 8; break; @@ -164,16 +172,22 @@ 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 (base_offset == -EDOM) + base = 0; + else if (base_offset < 0) goto out; + 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 (indx_offset == -EDOM) indx = 0; else if (indx_offset < 0) @@ -181,8 +195,6 @@ 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); |