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arch/sh: Check for kprobe trap number before trying to handle a kprobe trap

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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 <[email protected]>
Signed-off-by: Yoshinori Sato <[email protected]>
This commit is contained in:
Michael Karcher 2019-06-12 15:08:37 +02:00 • committed by Yoshinori Sato
commit d3023897b4
1 changed files with 2 additions and 1 deletions
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3
arch/sh/kernel/kprobes.c
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@ -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;