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-rw-r--r--kernel/kprobes.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 734e9a7..3995f54 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1778,7 +1778,18 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
unsigned long hash, flags = 0;
struct kretprobe_instance *ri;
- /*TODO: consider to only swap the RA after the last pre_handler fired */
+ /*
+ * To avoid deadlocks, prohibit return probing in NMI contexts,
+ * just skip the probe and increase the (inexact) 'nmissed'
+ * statistical counter, so that the user is informed that
+ * something happened:
+ */
+ if (unlikely(in_nmi())) {
+ rp->nmissed++;
+ return 0;
+ }
+
+ /* TODO: consider to only swap the RA after the last pre_handler fired */
hash = hash_ptr(current, KPROBE_HASH_BITS);
raw_spin_lock_irqsave(&rp->lock, flags);
if (!hlist_empty(&rp->free_instances)) {
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