[PATCH -tip v3 04/10] x86/kprobes: Prohibit probing on IRQ handlers directly

Masami Hiramatsu
2019-02-12T16:13:09Z

Prohibit probing on IRQ handlers in irqentry_text because
if it interrupts user mode, at that point we haven't changed
to kernel space yet and which eventually leads a double fault.
E.g.

# echo p apic_timer_interrupt > kprobe_events
# echo 1 > events/kprobes/enable
PANIC: double fault, error_code: 0x0
CPU: 1 PID: 814 Comm: less Not tainted 4.20.0-rc3+ #30
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:error_entry+0x12/0xf0
[snip]
Call Trace:
<ENTRY_TRAMPOLINE>
? native_iret+0x7/0x7
? async_page_fault+0x8/0x30
? trace_hardirqs_on_thunk+0x1c/0x1c
? error_entry+0x7c/0xf0
? async_page_fault+0x8/0x30
? native_iret+0x7/0x7
? int3+0xa/0x20
? trace_hardirqs_on_thunk+0x1c/0x1c
? error_entry+0x7c/0xf0
? int3+0xa/0x20
? apic_timer_interrupt+0x1/0x20
</ENTRY_TRAMPOLINE>
Kernel panic - not syncing: Machine halted.
Kernel Offset: disabled
---[ end Kernel panic - not syncing: Machine halted. ]---

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
arch/x86/kernel/kprobes/core.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 4ba75afba527..a034cb808e7e 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -1028,6 +1028,13 @@ NOKPROBE_SYMBOL(kprobe_fault_handler);

int __init arch_populate_kprobe_blacklist(void)
{
+ int ret;
+
+ ret = kprobe_add_area_blacklist((unsigned long)__irqentry_text_start,
+ (unsigned long)__irqentry_text_end);
+ if (ret)
+ return ret;
+
return kprobe_add_area_blacklist((unsigned long)__entry_text_start,
(unsigned long)__entry_text_end);
}