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Date:   Thu, 28 Oct 2021 18:37:49 -0400
From:   Zekun Shen <bruceshenzk@gmail.com>
To:     bruceshenzk@gmail.com
Cc:     Pontus Fuchs <pontus.fuchs@gmail.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] ar5523: Fix null-ptr-deref with unexpected
 WDCMSG_TARGET_START reply
Message-ID: <YXsmPQ3awHFLuAj2@10-18-43-117.dynapool.wireless.nyu.edu>
MIME-Version: 1.0
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Precedence: bulk

Unexpected WDCMSG_TARGET_START replay can lead to null-ptr-deref
when ar->tx_cmd->odata is NULL. The patch adds a null check to
prevent such case.

KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
 ar5523_cmd+0x46a/0x581 [ar5523]
 ar5523_probe.cold+0x1b7/0x18da [ar5523]
 ? ar5523_cmd_rx_cb+0x7a0/0x7a0 [ar5523]
 ? __pm_runtime_set_status+0x54a/0x8f0
 ? _raw_spin_trylock_bh+0x120/0x120
 ? pm_runtime_barrier+0x220/0x220
 ? __pm_runtime_resume+0xb1/0xf0
 usb_probe_interface+0x25b/0x710
 really_probe+0x209/0x5d0
 driver_probe_device+0xc6/0x1b0
 device_driver_attach+0xe2/0x120

Signed-off-by: Zekun Shen <bruceshenzk@gmail.com>
---
 drivers/net/wireless/ath/ar5523/ar5523.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/wireless/ath/ar5523/ar5523.c b/drivers/net/wireless/ath/ar5523/ar5523.c
index 49cc4b7ed..1baec4b41 100644
--- a/drivers/net/wireless/ath/ar5523/ar5523.c
+++ b/drivers/net/wireless/ath/ar5523/ar5523.c
@@ -153,6 +153,10 @@ static void ar5523_cmd_rx_cb(struct urb *urb)
 			ar5523_err(ar, "Invalid reply to WDCMSG_TARGET_START");
 			return;
 		}
+		if (!cmd->odata) {
+			ar5523_err(ar, "Unexpected WDCMSG_TARGET_START reply");
+			return;
+		}
 		memcpy(cmd->odata, hdr + 1, sizeof(u32));
 		cmd->olen = sizeof(u32);
 		cmd->res = 0;
-- 
2.25.1