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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@kernel.org>
To:     Alexander Potapenko <glider@google.com>, glider@google.com
Cc:     ath9k-devel@qca.qualcomm.com, davem@davemloft.net, kuba@kernel.org,
        kvalo@codeaurora.org, linux-kernel@vger.kernel.org,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        syzbot+2ca247c2d60c7023de7f@syzkaller.appspotmail.com
Subject: Re: [PATCH] ath9k: fix an uninit value use in ath9k_htc_rx_msg()
In-Reply-To: <20220825080555.3643572-1-glider@google.com>
References: <20220825080555.3643572-1-glider@google.com>
Date:   Fri, 07 Oct 2022 19:37:12 +0200
Message-ID: <87leprcz7b.fsf@toke.dk>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Alexander Potapenko <glider@google.com> writes:

> ath9k_htc_rx_msg() assumes skb->data contains a full
> `struct htc_frame_hdr`, thus it needs a call to pskb_may_pull()
> to ensure there is enough data.
>
> This fixes a long-standing issue reported by KMSAN:
>
>   BUG: KMSAN: uninit-value in ath9k_htc_rx_msg+0x544/0x980 drivers/net/wireless/ath/ath9k/htc_hst.c:417
>    ath9k_htc_rx_msg+0x544/0x980 drivers/net/wireless/ath/ath9k/htc_hst.c:417
>    ath9k_hif_usb_rx_stream drivers/net/wireless/ath/ath9k/hif_usb.c:653 [inline]
>    ath9k_hif_usb_rx_cb+0x196a/0x1f10 drivers/net/wireless/ath/ath9k/hif_usb.c:686
>    __usb_hcd_giveback_urb+0x522/0x740 drivers/usb/core/hcd.c:1670
>    usb_hcd_giveback_urb+0x150/0x620 drivers/usb/core/hcd.c:1747
>    dummy_timer+0xd3f/0x4f20 drivers/usb/gadget/udc/dummy_hcd.c:1988
>    call_timer_fn+0x43/0x480 kernel/time/timer.c:1474
>    expire_timers+0x272/0x610 kernel/time/timer.c:1519
>    __run_timers+0x5bc/0x8c0 kernel/time/timer.c:1790
>   ...
>
>   Uninit was created at:
>   ...
>    __alloc_skb+0x34a/0xd70 net/core/skbuff.c:426
>    __netdev_alloc_skb+0x126/0x780 net/core/skbuff.c:494
>    __dev_alloc_skb include/linux/skbuff.h:3264 [inline]
>    ath9k_hif_usb_rx_stream drivers/net/wireless/ath/ath9k/hif_usb.c:635 [inline]
>    ath9k_hif_usb_rx_cb+0xe7b/0x1f10 drivers/net/wireless/ath/ath9k/hif_usb.c:686
>    __usb_hcd_giveback_urb+0x522/0x740 drivers/usb/core/hcd.c:1670
>   ...
>
> Reported-by: syzbot+2ca247c2d60c7023de7f@syzkaller.appspotmail.com
> Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
> Signed-off-by: Alexander Potapenko <glider@google.com>

This has been fixed (in a different way) by commit:
b383e8abed41 ("wifi: ath9k: avoid uninit memory read in ath9k_htc_rx_msg()")

-Toke