Re: [syzbot] Re: 000000000000fcfa6406141cc8ac@xxxxxxxxxx

[syzbot]

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Subject: Re: 000000000000fcfa6406141cc8ac@xxxxxxxxxx
Author: wojciech.gladysz@xxxxxxxxxxxx

#syz test: https://linux.googlesource.com/linux/kernel/git/torvalds/linux e377d803b65ee4130213b3c041fc25fdfec1bd90
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2393,12 +2393,21 @@ void __bpf_trace_run(struct bpf_raw_tp_link *link, u64 *args)
        cant_sleep();

        // return if instrumentation disabled, see: bpf_disable_instrumentation
-       if (unlikely(__this_cpu_read(bpf_prog_active))) {
+       int instrumentation = unlikely(__this_cpu_read(bpf_prog_active));
+       if (instrumentation) {
+               printk("SKIP FOR INSTRUMENTATION: %s > %s > %p /%i ==============\n",
+                               prog->aux->name,
+                               link->btp->tp->name, prog, instrumentation);
                bpf_prog_inc_misses_counter(prog);
                return;
        }

-       if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) {
+       int active = this_cpu_inc_return(*(prog->active));
+       printk("%s > %s > %p /%i\n", prog->aux->name, link->btp->tp->name, prog, active);
+       if (active != 1) {
+               printk("SKIP FOR ACTIVE: %s > %s > %p /%i =======================\n",
+                               prog->aux->name,
+                               link->btp->tp->name, prog, active);
                bpf_prog_inc_misses_counter(prog);
                goto out;
        }
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 8d1507dd0724..f852d7b86ff4 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -298,6 +308,8 @@ static enum tp_func_state nr_func_state(const struct tracepoint_func *tp_funcs)
 {
        if (!tp_funcs)
                return TP_FUNC_0;
+       if (!tp_funcs[0].func)
+               return TP_FUNC_0;
        if (!tp_funcs[1].func)
                return TP_FUNC_1;
        if (!tp_funcs[2].func)
--
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