On Thu, Jul 03, 2025 at 01:48:14PM -0700, Kumar Kartikeya Dwivedi wrote:
> +static void bpf_prog_report_rqspinlock_violation(const char *str, void
> *lock, bool irqsave)
> +{
> + struct rqspinlock_held *rqh = this_cpu_ptr(&rqspinlock_held_locks);
> + struct bpf_stream_stage ss;
> + struct bpf_prog *prog;
> +
> + prog = bpf_prog_find_from_stack();
> + if (!prog)
> + return;
> + bpf_stream_stage(ss, prog, BPF_STDERR, ({
> + bpf_stream_printk(ss, "ERROR: %s for bpf_res_spin_lock%s\n",
> str, irqsave ? "_irqsave" : "");
> + bpf_stream_printk(ss, "Attempted lock = 0x%px\n", lock);
> + bpf_stream_printk(ss, "Total held locks = %d\n", rqh->cnt);
> + for (int i = 0; i < min(RES_NR_HELD, rqh->cnt); i++)
> + bpf_stream_printk(ss, "Held lock[%2d] = 0x%px\n", i,
> rqh->locks[i]);
> + bpf_stream_dump_stack(ss);
Please don't include %px in stuff going back to userspace in standard
error reporting. That's a kernel address leak:
https://docs.kernel.org/process/deprecated.html#p-format-specifier
I don't see any justification here, please remove the lock address or
use regular %p to get a hashed value.
--
Kees Cook
