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From:   Harshitha Prem <quic_hprem@quicinc.com>
To:     ath12k@lists.infradead.org
Cc:     linux-wireless@vger.kernel.org,
        Harshitha Prem <quic_hprem@quicinc.com>
Subject: [PATCH 2/2] wifi: ath12k: fix undefined behavior with __fls in dp
Date:   Wed,  9 Aug 2023 09:57:38 +0530
Message-Id: <20230809042738.13394-3-quic_hprem@quicinc.com>
In-Reply-To: <20230809042738.13394-1-quic_hprem@quicinc.com>
References: <20230809042738.13394-1-quic_hprem@quicinc.com>
Precedence: bulk

When max virtual ap interfaces are configured in all the bands
with ACS and hostapd restart is done every 60s,
a crash is observed at random times because of handling the
uninitialized peer fragments.

During the crash, the fragment id of that packet was 0 and
__fls returned a junk value. Hence, it was identified that "__fls"
would have an undefined behavior if the argument is passed as "0".
Therefore, add changes to handle the same.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1

Signed-off-by: Harshitha Prem <quic_hprem@quicinc.com>
---
 drivers/net/wireless/ath/ath12k/dp_rx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath12k/dp_rx.c b/drivers/net/wireless/ath/ath12k/dp_rx.c
index 5923c7c9eaff..ea8dfea22be6 100644
--- a/drivers/net/wireless/ath/ath12k/dp_rx.c
+++ b/drivers/net/wireless/ath/ath12k/dp_rx.c
@@ -3238,7 +3238,7 @@ static int ath12k_dp_rx_frag_h_mpdu(struct ath12k *ar,
 		goto out_unlock;
 	}
 
-	if (frag_no > __fls(rx_tid->rx_frag_bitmap))
+	if ((!rx_tid->rx_frag_bitmap || frag_no > __fls(rx_tid->rx_frag_bitmap)))
 		__skb_queue_tail(&rx_tid->rx_frags, msdu);
 	else
 		ath12k_dp_rx_h_sort_frags(ab, &rx_tid->rx_frags, msdu);
-- 
2.17.1