From d3023897b4370bbf7f289806667a2380576d13dd Mon Sep 17 00:00:00 2001
From: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
Date: Wed, 12 Jun 2019 15:08:37 +0200
Subject: [PATCH] arch/sh: Check for kprobe trap number before trying to handle
a kprobe trap
The DIE_TRAP notifier chain is run both for kprobe traps and for BUG/WARN
traps. The kprobe code assumes to be only called for
BREAKPOINT_INSTRUCTION, and concludes to have hit a concurrently removed
kprobe if it finds anything else at the faulting locations. This includes
TRAPA_BUG_OPCODE used for BUG and WARN.
The consequence is that kprobe_handler returns 1. This makes
kprobe_exceptions_notify return NOTIFY_STOP, and prevents handling the BUG
statement. This also prevents moving $pc away from the trap instruction,
so the system locks up in an endless loop
Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
---
arch/sh/kernel/kprobes.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
index 1f8c0d30567fe..318296f48f1ac 100644
--- a/arch/sh/kernel/kprobes.c
+++ b/arch/sh/kernel/kprobes.c
@@ -485,7 +485,8 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
addr = (kprobe_opcode_t *) (args->regs->pc);
- if (val == DIE_TRAP) {
+ if (val == DIE_TRAP &&
+ args->trapnr == (BREAKPOINT_INSTRUCTION & 0xff)) {
if (!kprobe_running()) {
if (kprobe_handler(args->regs)) {
ret = NOTIFY_STOP;
--
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