41 lines
1.6 KiB
Diff
41 lines
1.6 KiB
Diff
From 6d7cc74d8aad33589c6cc6f38e33c4284abc07b8 Mon Sep 17 00:00:00 2001
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From: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
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Date: Wed, 12 Jun 2019 15:08:37 +0200
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Subject: [PATCH 1/1] arch/sh: Check for kprobe trap number before trying to
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handle a kprobe trap
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Origin: https://marc.info/?l=linux-sh&m=156034655921917&w=2
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The DIE_TRAP notifier chain is run both for kprobe traps and for BUG/WARN
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traps. The kprobe code assumes to be only called for
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BREAKPOINT_INSTRUCTION, and concludes to have hit a concurrently removed
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kprobe if it finds anything else at the faulting locations. This includes
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TRAPA_BUG_OPCODE used for BUG and WARN.
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The consequence is that kprobe_handler returns 1. This makes
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kprobe_exceptions_notify return NOTIFY_STOP, and prevents handling the BUG
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statement. This also prevents moving $pc away from the trap instruction,
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so the system locks up in an endless loop
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Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
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---
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arch/sh/kernel/kprobes.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c
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index 1f8c0d30567f..318296f48f1a 100644
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--- a/arch/sh/kernel/kprobes.c
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+++ b/arch/sh/kernel/kprobes.c
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@@ -485,7 +485,8 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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addr = (kprobe_opcode_t *) (args->regs->pc);
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- if (val == DIE_TRAP) {
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+ if (val == DIE_TRAP &&
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+ args->trapnr == (BREAKPOINT_INSTRUCTION & 0xff)) {
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if (!kprobe_running()) {
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if (kprobe_handler(args->regs)) {
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ret = NOTIFY_STOP;
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--
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2.11.0
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