linux-cve-announce - CVE-2025-39887: tracing/osnoise: Fix null-ptr-deref in bitmap

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Message-ID: <2025092302-CVE-2025-39887-12f0@gregkh>
Date: Tue, 23 Sep 2025 08:01:18 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39887: tracing/osnoise: Fix null-ptr-deref in bitmap_parselist()

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

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

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

tracing/osnoise: Fix null-ptr-deref in bitmap_parselist()

A crash was observed with the following output:

BUG: kernel NULL pointer dereference, address: 0000000000000010
Oops: Oops: 0000 [#1] SMP NOPTI
CPU: 2 UID: 0 PID: 92 Comm: osnoise_cpus Not tainted 6.17.0-rc4-00201-gd69eb204c255 #138 PREEMPT(voluntary)
RIP: 0010:bitmap_parselist+0x53/0x3e0
Call Trace:
 <TASK>
 osnoise_cpus_write+0x7a/0x190
 vfs_write+0xf8/0x410
 ? do_sys_openat2+0x88/0xd0
 ksys_write+0x60/0xd0
 do_syscall_64+0xa4/0x260
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
 </TASK>

This issue can be reproduced by below code:

fd=open("/sys/kernel/debug/tracing/osnoise/cpus", O_WRONLY);
write(fd, "0-2", 0);

When user pass 'count=0' to osnoise_cpus_write(), kmalloc() will return
ZERO_SIZE_PTR (16) and cpulist_parse() treat it as a normal value, which
trigger the null pointer dereference. Add check for the parameter 'count'.

The Linux kernel CVE team has assigned CVE-2025-39887 to this issue.

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

	Issue introduced in 6.16 with commit 17f89102fe23d7389085a8820550df688f79888a and fixed in 6.16.8 with commit e33228a2cc7ff706ca88533464e8a3b525b961ed
	Issue introduced in 6.16 with commit 17f89102fe23d7389085a8820550df688f79888a and fixed in 6.17-rc6 with commit c1628c00c4351dd0727ef7f670694f68d9e663d8

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-2025-39887
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/trace/trace_osnoise.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/e33228a2cc7ff706ca88533464e8a3b525b961ed
	https://git.kernel.org/stable/c/c1628c00c4351dd0727ef7f670694f68d9e663d8