linux-cve-announce - CVE-2022-50639: io-wq: Fix memory leak in worker creation

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Message-ID: <2025120935-CVE-2022-50639-789f@gregkh>
Date: Tue,  9 Dec 2025 09:01:40 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50639: io-wq: Fix memory leak in worker creation

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

io-wq: Fix memory leak in worker creation

If the CPU mask allocation for a node fails, then the memory allocated for
the 'io_wqe' struct of the current node doesn't get freed on the error
handling path, since it has not yet been added to the 'wqes' array.

This was spotted when fuzzing v6.1-rc1 with Syzkaller:
BUG: memory leak
unreferenced object 0xffff8880093d5000 (size 1024):
  comm "syz-executor.2", pid 7701, jiffies 4295048595 (age 13.900s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000cb463369>] __kmem_cache_alloc_node+0x18e/0x720
    [<00000000147a3f9c>] kmalloc_node_trace+0x2a/0x130
    [<000000004e107011>] io_wq_create+0x7b9/0xdc0
    [<00000000c38b2018>] io_uring_alloc_task_context+0x31e/0x59d
    [<00000000867399da>] __io_uring_add_tctx_node.cold+0x19/0x1ba
    [<000000007e0e7a79>] io_uring_setup.cold+0x1b80/0x1dce
    [<00000000b545e9f6>] __x64_sys_io_uring_setup+0x5d/0x80
    [<000000008a8a7508>] do_syscall_64+0x5d/0x90
    [<000000004ac08bec>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

The Linux kernel CVE team has assigned CVE-2022-50639 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.14 with commit 0e03496d1967abf1ebb151a24318c07d07f41f7f and fixed in 5.15.75 with commit b6e2c54be37d5eb4f6666e6aa59cd0581c7ffc3c
	Issue introduced in 5.14 with commit 0e03496d1967abf1ebb151a24318c07d07f41f7f and fixed in 6.0.4 with commit ed981911a7c90a604f4a2bee908ab07e3b786aca
	Issue introduced in 5.14 with commit 0e03496d1967abf1ebb151a24318c07d07f41f7f and fixed in 6.1 with commit 996d3efeb091c503afd3ee6b5e20eabf446fd955

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-50639
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	io_uring/io-wq.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/b6e2c54be37d5eb4f6666e6aa59cd0581c7ffc3c
	https://git.kernel.org/stable/c/ed981911a7c90a604f4a2bee908ab07e3b786aca
	https://git.kernel.org/stable/c/996d3efeb091c503afd3ee6b5e20eabf446fd955