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Subject: Re: [PATCH] p54: fix crash during initialization
From:   Kalle Valo <kvalo@codeaurora.org>
In-Reply-To: <20190518200548.7662-1-chunkeey@gmail.com>
References: <20190518200548.7662-1-chunkeey@gmail.com>
To:     Christian Lamparter <chunkeey@gmail.com>
Cc:     linux-wireless@vger.kernel.org,
        "David S . Miller" <davem@davemloft.net>
User-Agent: pwcli/0.0.0-git (https://github.com/kvalo/pwcli/) Python/2.7.12
Message-Id: <20190528122650.1D35960A05@smtp.codeaurora.org>
Date:   Tue, 28 May 2019 12:26:50 +0000 (UTC)
Sender: linux-wireless-owner@vger.kernel.org
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Christian Lamparter <chunkeey@gmail.com> wrote:

> This patch fixes a crash that got introduced when the
> mentioned patch replaced  the direct list_head access
> with skb_peek_tail(). When the device is starting up,
> there are  no entries in  the queue, so previously to
> "Use skb_peek_tail() instead..." the target_skb would
> end up as the  tail and head pointer which then could
> be used by __skb_queue_after to fill the empty queue.
> 
> With skb_peek_tail() in its place will instead just
> return NULL which then causes a crash in the
> __skb_queue_after().
> 
> | BUG: unable to handle kernel NULL pointer dereference at 000000
> | #PF error: [normal kernel read fault]
> | PGD 0 P4D 0
> | Oops: 0000 [#1] SMP PTI
> | CPU: 0 PID: 12 Comm: kworker/0:1 Tainted: GO   5.1.0-rc7-wt+ #218
> | Hardware name: MSI MS-7816/Z87-G43 (MS-7816), BIOS V1.11 05/09/2015
> | Workqueue: events request_firmware_work_func
> | RIP: 0010:p54_tx_pending+0x10f/0x1b0 [p54common]
> | Code: 78 06 80 78 28 00 74 6d <48> 8b 07 49 89 7c 24 08 49 89 04 24 4
> | RSP: 0018:ffffa81c81927d90 EFLAGS: 00010086
> | RAX: ffff9bbaaf131048 RBX: 0000000000020670 RCX: 0000000000020264
> | RDX: ffff9bbaa976d660 RSI: 0000000000000202 RDI: 0000000000000000
> | RBP: ffff9bbaa976d620 R08: 00000000000006c0 R09: ffff9bbaa976d660
> | R10: 0000000000000000 R11: ffffe8480dbc5900 R12: ffff9bbb45e87700
> | R13: ffff9bbaa976d648 R14: ffff9bbaa976d674 R15: ffff9bbaaf131048
> | FS:  0000000000000000(0000) GS:ffff9bbb5ec00000(0000) knlGS:00000
> | CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> | CR2: 0000000000000000 CR3: 00000003695fc003 CR4: 00000000001606f0
> | Call Trace:
> |  p54_download_eeprom+0xbe/0x120 [p54common]
> |  p54_read_eeprom+0x7f/0xc0 [p54common]
> |  p54u_load_firmware_cb+0xe0/0x160 [p54usb]
> |  request_firmware_work_func+0x42/0x80
> |  process_one_work+0x1f5/0x3f0
> |  worker_thread+0x28/0x3c0
> 
> Cc: stable@vger.kernel.org
> Fixes: e3554197fc8f ("p54: Use skb_peek_tail() instead of direct head pointer accesses.")
> Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

Patch applied to wireless-drivers-next.git, thanks.

1645ab931998 p54: fix crash during initialization

-- 
https://patchwork.kernel.org/patch/10949055/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches