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Date: Tue, 24 May 2022 09:10:37 -0700
From: Kyle Zeng <>
Subject: CVE-2022-1786: Linux Kernel invalid-free in io_uring

Hi there,

I recently found a severe invalid-free bug in the io_uring subsystem
which affects Linux kernel v5.10. It has been demonstrated that the
vulnerability can be exploited to achieve local privilege escalation.

# Root Cause
The root cause of the bug is a misuse of the identity model in
io_uring. When preparing a request, the kernel uses the identity of
the current task instead of that of the request task, which causes
type confusion and invalid-free when the request needs to be

# Impact
I wrote a proof-of-concept exploit and demonstrated that it can be
used to achieve local privilege escalation.

# Affected Versions
To the best of my knowledge, this bug only affects Linux kernel v5.10
and v5.11 because of their unique identity model in io_uring. But it
still affects many users because of some widely used vendors (Android
12, ChromeOS, etc).

# Disclosure & Patch
I already contacted the Linux security team and prepared a patch. The
patch has been merged into the Linux kernel stable tree and it can be
found here:

I also informed the vendors and gave enough time for them to patch the
bug before this public disclosure.

Kyle Zeng

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