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

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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: stable@vger.kernel.org # 5.7 Signed-off-by: Johan Hovold johan+linaro@kernel.org

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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); }