Sorry for delay, vacation.
On 09/03, Hemant Kumar Shaw wrote:
>
> There exists a limit to the number of nested return probes. The current limit
> is 64.
> However this limit is getting enforced on even non nested return probes.
> Hence, registering 64 independent non nested return probes results in failure
> of
> return probes on the same task. The problem is utask->depth is getting
> incremented
> unconditionally but decremented only if chained.
Hmm. I'll try to recheck later, but at first glance this logic is indeed
wrong, thanks.
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1442,7 +1442,8 @@ static void prepare_uretprobe(struct uprobe *uprobe,
> struct pt_regs *regs)
> ri->orig_ret_vaddr = orig_ret_vaddr;
> ri->chained = chained;
>
> - utask->depth++;
> + if (chained)
> + utask->depth++;
Not sure, but I can be easily wrong... afaics we need something like below, no?
Anton?
Oleg.
--- x/kernel/events/uprobes.c
+++ x/kernel/events/uprobes.c
@@ -1682,12 +1682,10 @@ static bool handle_trampoline(struct pt_
tmp = ri;
ri = ri->next;
kfree(tmp);
+ utask->depth--;
if (!chained)
break;
-
- utask->depth--;
-
BUG_ON(!ri);
}
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