On 10/19/2023 3:42 AM, Johan Hovold wrote:
> The ath11k active pdevs are protected by RCU but the temperature event
> handling code calling ath11k_mac_get_ar_by_pdev_id() was not marked as a
> read-side critical section as reported by RCU lockdep:
How do I enable this? Just enable CONFIG_PROVE_RCU?
Of course I'd also need to exercise the code path...
>
> =============================
> WARNING: suspicious RCU usage
> 6.6.0-rc6 #7 Not tainted
> -----------------------------
> drivers/net/wireless/ath/ath11k/mac.c:638 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> no locks held by swapper/0/0.
> ...
> Call trace:
> ...
> lockdep_rcu_suspicious+0x16c/0x22c
> ath11k_mac_get_ar_by_pdev_id+0x194/0x1b0 [ath11k]
> ath11k_wmi_tlv_op_rx+0xa84/0x2c1c [ath11k]
> ath11k_htc_rx_completion_handler+0x388/0x510 [ath11k]
>
> Mark the code in question as an RCU read-side critical section to avoid
> any potential use-after-free issues.
>
> Fixes: a41d10348b01 ("ath11k: add thermal sensor device support")
> Cc: [email protected] # 5.7
> Signed-off-by: Johan Hovold <[email protected]>
> ---
> drivers/net/wireless/ath/ath11k/wmi.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath11k/wmi.c b/drivers/net/wireless/ath/ath11k/wmi.c
> index 23ad6825e5be..980ff588325d 100644
> --- a/drivers/net/wireless/ath/ath11k/wmi.c
> +++ b/drivers/net/wireless/ath/ath11k/wmi.c
> @@ -8383,6 +8383,8 @@ ath11k_wmi_pdev_temperature_event(struct ath11k_base *ab,
> ath11k_dbg(ab, ATH11K_DBG_WMI, "event pdev temperature ev temp %d pdev_id %d\n",
> ev->temp, ev->pdev_id);
>
> + rcu_read_lock();
> +
> ar = ath11k_mac_get_ar_by_pdev_id(ab, ev->pdev_id);
> if (!ar) {
> ath11k_warn(ab, "invalid pdev id in pdev temperature ev %d", ev->pdev_id);
aren't you missing an unlock() in this error path?
perhaps have a goto cleanup that does both the unlock() and the kfree()?
> @@ -8392,6 +8394,8 @@ ath11k_wmi_pdev_temperature_event(struct ath11k_base *ab,
>
> ath11k_thermal_event_temperature(ar, ev->temp);
>
> + rcu_read_unlock();
> +
> kfree(tb);
> }
>