Re: [syzbot] Re: 000000000000fcfa6406141cc8ac@google.com

[syzbot <syzbot+9d95beb2a3c260622518@syzkaller.appspotmail.com>]

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Subject: Re: 000000000000fcfa6406141cc8ac@google.com
Author: wojciech.gladysz@infogain.com

#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;
      }
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -67,7 +67,7 @@ static void tp_rcu_cond_sync(enum tp_transition_sync sync)
 }

 /* Set to 1 to enable tracepoint debug output */
-static const int tracepoint_debug;
+static const int tracepoint_debug=1;

 #ifdef CONFIG_MODULES
 /*
@@ -298,6 +298,8 @@ 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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