linux-kernel - Re: [BUG] media: cx88-alsa: Found a bug at the probe time

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Date:   Sat, 16 Jul 2022 12:03:25 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Zheyu Ma <zheyuma97@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Cc:     linux-media <linux-media@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] media: cx88-alsa: Found a bug at the probe time

Hi--

On 7/14/22 18:54, Zheyu Ma wrote:
> Hello,
> 
> I found a bug in the driver cx88-alsa.
> 
> When the driver fails in the function snd_cx88_create() at the probe
> time, it will cause a UAF bug as follows:

It's not a UAF. It's a WARN() macro with an IRQ management problem,
as shown in the next 2 lines below:
> 
> [   24.343899] Trying to free already-free IRQ 0
> [   24.344815] WARNING: CPU: 7 PID: 389 at kernel/irq/manage.c:1895
> free_irq+0x3a4/0x7c0
> [   24.348448] RIP: 0010:free_irq+0x3a4/0x7c0
> [   24.356716] Call Trace:
> [   24.357124]  snd_cx88_dev_free+0x71/0x100 [cx88_alsa]
> [   24.358008]  release_card_device+0x7d/0x190
> [   24.358699]  device_release+0x97/0x1c0
> [   24.359022]  kobject_put+0x144/0x1c0
> [   24.359329]  snd_card_free+0xec/0x150
> [   24.360078]  cx88_audio_initdev+0x8f4/0xce0 [cx88_alsa]
> 
> Since I'm not familiar with the driver, could you please give me some
> hints to fix it?
> 
> regards,
> 
> Zheyu Ma

-- 
~Randy