From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A253849E15F for ; Fri, 11 Sep 2026 20:05:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789157148; cv=none; b=CNxrNRlkugu5KUUUg8uTAk1WOh+NIEVCmyLbAEbEH/ViBwufm/mpiLHp1mXWP4855S5LxE05z/GEkXRGdVYBBLB+9e65ovL7F85GfKO7PGllHvOa4WP6mxYi0U1Bx/cbrm55sUsy03ThkqrDgBNKKd2HlXUuvy7wz3MxwEiotrY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789157148; c=relaxed/simple; bh=CAtx7thfvGF6h8OezngUr/C43vkOu72wLa48gK7Myu4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=E1XrZYAMke+CqCsU7HMpSlumMLGPlTRSimr7b4ztI9MKMH02xnOmqKg95iPNlOhEAkVVmD3AYkedjR5r9rq9XMS2Yr5AMTcj8dZSazA1WJzqEEAnL6AfFMSgLNNdinFgbK30rPRMJQva7KCJr9pAhKmp28oqg+NHdgZi7lhfoB0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=CmCmLIyB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="CmCmLIyB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 241AB1F000FF; Fri, 11 Sep 2026 20:05:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789157139; bh=7tI3Q9M8j4+o80WQilAxlz7rU3ovX4u7tZQhz1pA8pM=; h=From:To:Cc:Subject:Date:Reply-To; b=CmCmLIyBON3U8j/wctNP/mSNzgJQkL7J7LPiISPg0a72BYyLbkPL2lUnvR04rHO64 cRp97cBGQMx4y4FIEUDx3bLbHwUOAHI2bWlum5V6y9cfM7fD0rhEust2JURKMlUqQ6 t1RlTqMdEyQeslKrUwpxH6pHDT4c4d4MxryG82+Y= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89750: tracing/user_events: Clear copied tracing state before fork duplication Date: Fri, 11 Sep 2026 21:47:19 +0200 Message-ID: <2026091107-CVE-2026-89750-9fc4@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3583; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=I1LWa4D8fEgci712VQVbuB8aT8AtAuqzrSOrYm+tVu0=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIvsN+eJSrhxccfY1z3SVBbH83XkuW7ZI1P66tjj7b +BxrVOdHbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjCRIg+GOfzbha7n5Exrvic+ KyDGKkZE2DlzK8N8328baxfxMrqpnudxvXGjtDXH3aYFAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: tracing/user_events: Clear copied tracing state before fork duplication dup_task_struct() copies user_event_mm from the parent into the child, without grabbing a reference to it. user_event_mm_dup() should replace it, but it leaves that copied pointer unmodified if user_event_mm_alloc() fails. When the child exits, user_event_mm_remove() decrements a reference the child never owned, which ultimately frees user_event_mm, while the parent still as a stale pointer to it. This creates a UAF, which KASAN reports as: BUG: KASAN: slab-use-after-free in current_user_event_mm+0x51/0x1d0 Write of size 4 at addr ffff888005010d30 by task init/44 Call Trace: kasan_report+0xce/0x100 kasan_check_range+0x10f/0x1e0 current_user_event_mm+0x51/0x1d0 user_events_ioctl+0x82e/0x15c0 __x64_sys_ioctl+0x139/0x1c0 do_syscall_64+0xce/0x450 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated by task 44: __kasan_kmalloc+0x8f/0xa0 __kmalloc_cache_noprof+0x180/0x3a0 user_event_mm_alloc+0x3c/0x1f0 current_user_event_mm+0x88/0x1d0 Freed by task 42: __kasan_slab_free+0x43/0x70 kfree+0x13a/0x390 process_one_work+0x696/0xf90 worker_thread+0x420/0xba0 The fix simply clears the copied pointer before any possible failure. In case of failure, the child then has nothing to free. The Linux kernel CVE team has assigned CVE-2026-89750 to this issue. Affected and fixed versions =========================== Issue introduced in 6.4 with commit 7235759084a4f8524a46bd2638885ff3b34ce279 and fixed in 6.12.109 with commit 63b39e49a4c9d68e010e96b26fc7374f0864f2b1 Issue introduced in 6.4 with commit 7235759084a4f8524a46bd2638885ff3b34ce279 and fixed in 6.18.50 with commit 25a0758cf6bdbfddac2be71124c9bd0692f4b0b1 Issue introduced in 6.4 with commit 7235759084a4f8524a46bd2638885ff3b34ce279 and fixed in 7.2.4 with commit b799f67119aff179719a0b1e12441ebbdaaf62f9 Issue introduced in 6.4 with commit 7235759084a4f8524a46bd2638885ff3b34ce279 and fixed in 7.3-rc1 with commit 390f6bd8583d177029d9df4bea6667509e55a765 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-2026-89750 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_events_user.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/63b39e49a4c9d68e010e96b26fc7374f0864f2b1 https://git.kernel.org/stable/c/25a0758cf6bdbfddac2be71124c9bd0692f4b0b1 https://git.kernel.org/stable/c/b799f67119aff179719a0b1e12441ebbdaaf62f9 https://git.kernel.org/stable/c/390f6bd8583d177029d9df4bea6667509e55a765