linux-cve-announce - CVE-2023-53441: bpf: cpumap: Fix memory leak in cpu_map_update

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Message-ID: <2025091859-CVE-2023-53441-0641@gregkh>
Date: Thu, 18 Sep 2025 18:04:32 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53441: bpf: cpumap: Fix memory leak in cpu_map_update_elem

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

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

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

bpf: cpumap: Fix memory leak in cpu_map_update_elem

Syzkaller reported a memory leak as follows:

BUG: memory leak
unreferenced object 0xff110001198ef748 (size 192):
  comm "syz-executor.3", pid 17672, jiffies 4298118891 (age 9.906s)
  hex dump (first 32 bytes):
    00 00 00 00 4a 19 00 00 80 ad e3 e4 fe ff c0 00  ....J...........
    00 b2 d3 0c 01 00 11 ff 28 f5 8e 19 01 00 11 ff  ........(.......
  backtrace:
    [<ffffffffadd28087>] __cpu_map_entry_alloc+0xf7/0xb00
    [<ffffffffadd28d8e>] cpu_map_update_elem+0x2fe/0x3d0
    [<ffffffffadc6d0fd>] bpf_map_update_value.isra.0+0x2bd/0x520
    [<ffffffffadc7349b>] map_update_elem+0x4cb/0x720
    [<ffffffffadc7d983>] __se_sys_bpf+0x8c3/0xb90
    [<ffffffffb029cc80>] do_syscall_64+0x30/0x40
    [<ffffffffb0400099>] entry_SYSCALL_64_after_hwframe+0x61/0xc6

BUG: memory leak
unreferenced object 0xff110001198ef528 (size 192):
  comm "syz-executor.3", pid 17672, jiffies 4298118891 (age 9.906s)
  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:
    [<ffffffffadd281f0>] __cpu_map_entry_alloc+0x260/0xb00
    [<ffffffffadd28d8e>] cpu_map_update_elem+0x2fe/0x3d0
    [<ffffffffadc6d0fd>] bpf_map_update_value.isra.0+0x2bd/0x520
    [<ffffffffadc7349b>] map_update_elem+0x4cb/0x720
    [<ffffffffadc7d983>] __se_sys_bpf+0x8c3/0xb90
    [<ffffffffb029cc80>] do_syscall_64+0x30/0x40
    [<ffffffffb0400099>] entry_SYSCALL_64_after_hwframe+0x61/0xc6

BUG: memory leak
unreferenced object 0xff1100010fd93d68 (size 8):
  comm "syz-executor.3", pid 17672, jiffies 4298118891 (age 9.906s)
  hex dump (first 8 bytes):
    00 00 00 00 00 00 00 00                          ........
  backtrace:
    [<ffffffffade5db3e>] kvmalloc_node+0x11e/0x170
    [<ffffffffadd28280>] __cpu_map_entry_alloc+0x2f0/0xb00
    [<ffffffffadd28d8e>] cpu_map_update_elem+0x2fe/0x3d0
    [<ffffffffadc6d0fd>] bpf_map_update_value.isra.0+0x2bd/0x520
    [<ffffffffadc7349b>] map_update_elem+0x4cb/0x720
    [<ffffffffadc7d983>] __se_sys_bpf+0x8c3/0xb90
    [<ffffffffb029cc80>] do_syscall_64+0x30/0x40
    [<ffffffffb0400099>] entry_SYSCALL_64_after_hwframe+0x61/0xc6

In the cpu_map_update_elem flow, when kthread_stop is called before
calling the threadfn of rcpu->kthread, since the KTHREAD_SHOULD_STOP bit
of kthread has been set by kthread_stop, the threadfn of rcpu->kthread
will never be executed, and rcpu->refcnt will never be 0, which will
lead to the allocated rcpu, rcpu->queue and rcpu->queue->queue cannot be
released.

Calling kthread_stop before executing kthread's threadfn will return
-EINTR. We can complete the release of memory resources in this state.

The Linux kernel CVE team has assigned CVE-2023-53441 to this issue.


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

	Issue introduced in 4.15 with commit 6710e1126934d8b4372b4d2f9ae1646cd3f151bf and fixed in 5.15.121 with commit d26299f50f5ea8f0aeb5d49e659c31f64233c816
	Issue introduced in 4.15 with commit 6710e1126934d8b4372b4d2f9ae1646cd3f151bf and fixed in 6.1.40 with commit b11a9b4f28cb6ff69ef7e69809e5f7fffeac9030
	Issue introduced in 4.15 with commit 6710e1126934d8b4372b4d2f9ae1646cd3f151bf and fixed in 6.4.5 with commit a957ac8e0b5ffb5797382a6adbafd005a5f72851
	Issue introduced in 4.15 with commit 6710e1126934d8b4372b4d2f9ae1646cd3f151bf and fixed in 6.5 with commit 4369016497319a9635702da010d02af1ebb1849d

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-2023-53441
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:
	kernel/bpf/cpumap.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/d26299f50f5ea8f0aeb5d49e659c31f64233c816
	https://git.kernel.org/stable/c/b11a9b4f28cb6ff69ef7e69809e5f7fffeac9030
	https://git.kernel.org/stable/c/a957ac8e0b5ffb5797382a6adbafd005a5f72851
	https://git.kernel.org/stable/c/4369016497319a9635702da010d02af1ebb1849d