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Date:   Fri, 15 Jul 2022 08:58:54 +0200
Message-ID: <87a69ax3o1.wl-tiwai@suse.de>
From:   Takashi Iwai <tiwai@suse.de>
To:     Zheyu Ma <zheyuma97@gmail.com>
Cc:     perex@perex.cz, tiwai@suse.com, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ALSA: bcd2000: Fix a UAF bug on the error path of probing
In-Reply-To: <20220715010515.2087925-1-zheyuma97@gmail.com>
References: <20220715010515.2087925-1-zheyuma97@gmail.com>
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On Fri, 15 Jul 2022 03:05:15 +0200,
Zheyu Ma wrote:
> 
> When the driver fails in snd_card_register() at probe time, it will free
> the 'bcd2k->midi_out_urb' before killing it, which may cause a UAF bug.
> 
> The following log can reveal it:
> 
> [   50.727020] BUG: KASAN: use-after-free in bcd2000_input_complete+0x1f1/0x2e0 [snd_bcd2000]
> [   50.727623] Read of size 8 at addr ffff88810fab0e88 by task swapper/4/0
> [   50.729530] Call Trace:
> [   50.732899]  bcd2000_input_complete+0x1f1/0x2e0 [snd_bcd2000]
> 
> Fix this by adding usb_kill_urb() before usb_free_urb().
> 
> Fixes: b47a22290d58 ("ALSA: MIDI driver for Behringer BCD2000 USB device")
> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>

Thanks, applied.


Takashi