x86: kprobes bugfix
Kprobes for x86-64 may cause a kernel crash if it inserted on "iret"
instruction. "call absolute" is invalid on x86-64, so we don't need
treat it.
- Change the processing order as same as x86-32.
- Add "iret"(0xcf) case.
- Remove next_rip local variable.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/kprobes_64.c b/arch/x86/kernel/kprobes_64.c
index a575059..5df19a9 100644
--- a/arch/x86/kernel/kprobes_64.c
+++ b/arch/x86/kernel/kprobes_64.c
@@ -485,7 +485,6 @@
struct pt_regs *regs, struct kprobe_ctlblk *kcb)
{
unsigned long *tos = (unsigned long *)regs->rsp;
- unsigned long next_rip = 0;
unsigned long copy_rip = (unsigned long)p->ainsn.insn;
unsigned long orig_rip = (unsigned long)p->addr;
kprobe_opcode_t *insn = p->ainsn.insn;
@@ -494,46 +493,42 @@
if (*insn >= 0x40 && *insn <= 0x4f)
insn++;
+ regs->eflags &= ~TF_MASK;
switch (*insn) {
- case 0x9c: /* pushfl */
+ case 0x9c: /* pushfl */
*tos &= ~(TF_MASK | IF_MASK);
*tos |= kcb->kprobe_old_rflags;
break;
- case 0xc3: /* ret/lret */
- case 0xcb:
- case 0xc2:
+ case 0xc2: /* iret/ret/lret */
+ case 0xc3:
case 0xca:
- regs->eflags &= ~TF_MASK;
- /* rip is already adjusted, no more changes required*/
- return;
- case 0xe8: /* call relative - Fix return addr */
+ case 0xcb:
+ case 0xcf:
+ case 0xea: /* jmp absolute -- ip is correct */
+ /* ip is already adjusted, no more changes required */
+ goto no_change;
+ case 0xe8: /* call relative - Fix return addr */
*tos = orig_rip + (*tos - copy_rip);
break;
case 0xff:
if ((insn[1] & 0x30) == 0x10) {
/* call absolute, indirect */
- /* Fix return addr; rip is correct. */
- next_rip = regs->rip;
+ /* Fix return addr; ip is correct. */
*tos = orig_rip + (*tos - copy_rip);
+ goto no_change;
} else if (((insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */
((insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */
- /* rip is correct. */
- next_rip = regs->rip;
+ /* ip is correct. */
+ goto no_change;
}
- break;
- case 0xea: /* jmp absolute -- rip is correct */
- next_rip = regs->rip;
- break;
default:
break;
}
- regs->eflags &= ~TF_MASK;
- if (next_rip) {
- regs->rip = next_rip;
- } else {
- regs->rip = orig_rip + (regs->rip - copy_rip);
- }
+ regs->rip = orig_rip + (regs->rip - copy_rip);
+no_change:
+
+ return;
}
int __kprobes post_kprobe_handler(struct pt_regs *regs)
