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From: =?UTF-8?B?5YiY6YCa?= <lyutoon@gmail.com>
Date: Wed, 24 Apr 2024 14:12:07 +0800
Message-ID: <CAEJPjCv=M-RQhp4MkO9MPETsh8gpGOqrhNqXhe1Wm-nj1UTpUA@mail.gmail.com>
Subject: KASAN: use-after-free in snd_usbtv_pcm_close (with PoC and analysis)
To: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, 
	mchehab@kernel.org
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Hi upstream community,

I was fuzzing a LTS version of Linux kernel 5.15.148 with my modified
syzkaller and I found a bug named "KASAN: use-after-free in
snd_usbtv_pcm_close".

I tested the PoC on 5.5.148 ~ 6.8+ with sanitizer on and found
sanitizer through a panic as "KASAN: use-after-free in
snd_usbtv_pcm_close".

The syzkaller log, report, kernel config, PoC can be found here:
https://drive.google.com/file/d/12ubxzCGrkUVz8BWRwprHjRHYh3l0oMMd/view?usp=sharing

# Analysis:
I wrote an analysis to explain the root cause in an markdown file (in
Chinese, so you may use translators to read it... Sorry about that)
which can be found here:
https://drive.google.com/file/d/1-TjLRqLs1_C_MDgvAy-TURxldUabW2Eq/view?usp=sharing

# Step to reproduce:
1. download the zip file
2. unzip it
3. compile the kernel (5.15.148) with kernel_config
4. start the kernel with qemu vm
5. scp repro.c to the vm
6. compile the repro.cprog and run it: gcc repro.c -o exp && ./exp
7. you will see the KASAN error

# Note:
I didn't find any related reports on the internet, which indicates
that it may be a 0day. Hope the upstream can help check and fix it.
And I'll be happy to provide more information if needed.

Best,
Tong