From nobody Mon Sep 28 19:25:16 2026 Received: from zg8tmtyylji0my4xnjeumjiw.icoremail.net (zg8tmtyylji0my4xnjeumjiw.icoremail.net [162.243.161.220]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 48A8A30274D; Tue, 18 Aug 2026 08:12:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=162.243.161.220 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787040781; cv=none; b=csLZUQ2BF1BTvPCbHFBvtRBnn2T3cW4y3aYgzpqO1tYSQ3s46TweSGbDl4jD4EmK9TPyJrngWtZTBkEXRNJ3Hiu8c1rfjVX+vouwQNg2CrshJsMbWsygxy0J/9nxZNsPfBFmFkbLCd3MzwyM+Ycn1iLV5IIeNe+4Ov1tEuQmsTE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787040781; c=relaxed/simple; bh=8Rkk4e5WTxH3+6c3o6Adc8ngZf6wgKB9h5G6sxCUzg4=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=SHnK7c8wIQCUgFx2cYDIPvGzT2M94Gp1npOzVzQWMRyPASoohwcOYOwLgSkFQfi/siMBPiG6czcx1NKmRtpXWvFDn0PtoMD9Ifk/X0AN/vO2TZyWjKGAfvX+Adu8AyQclzzHpM5ZqBUZJ3ZPUSZp9/5TqxmjlhgC1mkf9pY+9Bs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn; spf=pass smtp.mailfrom=zju.edu.cn; arc=none smtp.client-ip=162.243.161.220 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zju.edu.cn Received: from zju.edu.cn (unknown [10.98.66.117]) by mtasvr (Coremail) with SMTP id _____wC3gX3zE4Rq0_uiAA--.35410S3; Tue, 18 Aug 2026 16:12:36 +0800 (CST) Received: from localhost.localdomain (unknown [10.98.66.117]) by mail-app3 (Coremail) with SMTP id zS_KCgA3T3HyE4RqELh4BA--.51434S2; Tue, 18 Aug 2026 16:12:35 +0800 (CST) From: Fan Wu To: hansg@kernel.org, arnd@arndb.de, gregkh@linuxfoundation.org Cc: virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Fan Wu Subject: [PATCH] virt: vboxguest: fix use-after-free in balloon work Date: Tue, 18 Aug 2026 08:11:39 +0000 Message-Id: <20260818081139.399994-1-fanwu01@zju.edu.cn> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: zS_KCgA3T3HyE4RqELh4BA--.51434S2 X-CM-SenderInfo: qrstjiaswqq6lmxovvfxof0/ X-CM-DELIVERINFO: =?B?wdwB/gXKKxbFmtjJiESix3B1w3vZ3A9ovKVTomAyoQazvoRs/NHSP8GI2EvgeEEW7R sfnZPoDCNGYdHSfuFmYJL54WNUZUskktimozYxW8ba9i/wgnDXgVi0t5G+j51kPNETvrdH TeUHjVrNU9pXGHEeLL2p9E6mavGmQbzmcFsnzP86 X-Coremail-Antispam: 1Uk129KBj93XoW7tFyrCrWkAr17Xw4fWr1kXrc_yoW8ZFykpr W3Cr9IkayUKF4Utw1xt3Wjva4ru3s2yr9rurW0vw1ayrsIyryjvr45CrWjvFZ5AF18KF1r trsYqr98KrWUJwcCm3ZEXasCq-sJn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUU9lb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AK xVW0oVCq3wAac4AC62xK8xCEY4vEwIxC4wAS0I0E0xvYzxvE52x082IY62kv0487Mc804V CY07AIYIkI8VC2zVCFFI0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AK xVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48Icx kI7VAKI48JM4x0Y48IcxkI7VAKI48G6xCjnVAKz4kxMxAIw28IcxkI7VAKI48JMxC20s02 6xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_Jr I_JrWlx4CE17CEb7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v2 6r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj4 0_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVWUJVW8 JbIYCTnIWIevJa73UjIFyTuYvjxU7gAwDUUUU Content-Type: text/plain; charset="utf-8" VMMDEV_EVENT_BALLOON_CHANGE_REQUEST is reported only after a guest userspace client enables it with VBOXGUEST_IOCTL_SET_EVENT_FILTER. The interrupt handler then queues the balloon work, which reads and writes the mem_balloon.get_req and change_req request buffers. vbg_pci_remove() calls free_irq() before vbg_core_exit(), but free_irq() only waits for the handler to return, not for any work it has queued. A balloon work still running on system_wq therefore touches the request buffers after vbg_core_exit() has freed them: CPU 0 (remove) IRQ handler system_wq free_irq() schedule_work(...) return vbg_core_exit() vbg_req_free(...) vbg_balloon_work() req->event_ack =3D ... Fix this by calling cancel_work_sync() on mem_balloon.work in vbg_core_exit(), before the request buffers are freed. The worker does not requeue itself, and the interrupt handler, the only place that queues it, can no longer run when vbg_core_exit() is reached: vbg_pci_remove() has already called free_irq(), and on the probe error path the irq was never requested. Draining the work once is therefore sufficient. This issue was found by an in-house static analysis tool. Fixes: 0ba002bc4393 ("virt: Add vboxguest driver for Virtual Box Guest inte= gration") Cc: stable@vger.kernel.org Assisted-by: Codex:gpt-5.6 Signed-off-by: Fan Wu Reviewed-by: Hans de Goede --- drivers/virt/vboxguest/vboxguest_core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/virt/vboxguest/vboxguest_core.c b/drivers/virt/vboxgue= st/vboxguest_core.c index b177a534b6a4..884e69d00f72 100644 --- a/drivers/virt/vboxguest/vboxguest_core.c +++ b/drivers/virt/vboxguest/vboxguest_core.c @@ -1048,6 +1048,8 @@ int vbg_core_init(struct vbg_dev *gdev, u32 fixed_eve= nts) */ void vbg_core_exit(struct vbg_dev *gdev) { + cancel_work_sync(&gdev->mem_balloon.work); + vbg_heartbeat_exit(gdev); vbg_guest_mappings_exit(gdev); =20 --=20 2.34.1