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Wed, 12 Aug 2026 20:02:52 +0000 (GMT) Received: from li-4c4c4544-004d-4810-8043-b7c04f423534.ibm.com.com (unknown [9.61.9.29]) by smtpav04.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 12 Aug 2026 20:02:51 +0000 (GMT) From: Anthony Krowiak To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: jjherne@linux.ibm.com, borntraeger@de.ibm.com, mjrosato@linux.ibm.com, pasic@linux.ibm.com, alex@shazbot.org, kwankhede@nvidia.com, fiuczy@linux.ibm.com, pbonzini@redhat.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com, agordeev@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, stable@vger.kernel.org Subject: [PATCH v5 6/9] s390/vfio-ap: fix potential use of uninitialized apm_filtered bitmap Date: Wed, 12 Aug 2026 16:02:37 -0400 Message-ID: <20260812200240.818004-7-akrowiak@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260812200240.818004-1-akrowiak@linux.ibm.com> References: <20260812200240.818004-1-akrowiak@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEyMDE2MSBTYWx0ZWRfX3tKEevlL5UUd w7KDqBgtIP0lC3MlXyXiOX+l5vuGgdIvUmfC54ZErxnLlv8spt11dp6muk33J6lYXjxb5wfVwnq 4WGcPx4f+0Xc+l4PKHCTcKuOI91yvKLW8U445BfMi5wGfOaYWnyQLw16jIpP5npL15Jvl6k2NPq qLU/CasIrZ7xkW/7av376Ma9hDbdHJokAQNxPubj9UrW81m5qAxVcvKhTCCiyogtW1sHwDrWoad l0+QBNws7teDWsh1EqDAP5G+/NSf7e2RZaQQTQxKOOSnRzDnZMK5RGJ5vjLB2u9trcZlEEnmlwY tC5tGAZVPUz11poYlWl/V5gO0Z9AZzrZKagqoP6GJ/oz/DXL5u8IChjshtMpkaGg4/IwmNAIHz5 bseOetNb8+sg0wxb9wJ47Z9XGUUyQt8P1NZC+3sDHbdcdVovJehe3qCbGRoUKljrv5OO8F534Zp 86M/TdecptVbXV9CGRg== X-Proofpoint-Spam-Info: AW1haW4tMjYwODEyMDE2MSBTYWx0ZWRfX0GbNygxCj9Sb tBevEwAPaMEEUZ3bRgHBqhq15Ox3bCjCjHyahFWHzD9NEqhFf+Ig8NTa6395km7cFu1mYzxwFvg PEAs0Eg9xffjOBocvWDmxZ9RcthwUqk= X-Authority-Analysis: v=2.4 cv=RqD16imK c=1 sm=1 tr=0 ts=6a7cd170 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=bGM9o4fjUnjFpbELYA8A:9 X-Proofpoint-GUID: 0t2RvG_dTqR7Et2V8lofGRZcplQ_W1eG X-Proofpoint-ORIG-GUID: 0t2RvG_dTqR7Et2V8lofGRZcplQ_W1eG X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-12_06,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 priorityscore=1501 suspectscore=0 lowpriorityscore=0 clxscore=1015 adultscore=0 bulkscore=0 malwarescore=0 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608120161 The DECLARE_BITMAP(apm_filtered, AP_DEVICES) macro allocates the bitmap on the stack without zero-initializing it. In vfio_ap_mdev_hot_plug_cfg(), the vfio_ap_mdev_filter_matrix() function is only called to initialize and populate apm_filtered if either filter_adapters or filter_domains is true. If the hot plug configuration change only adds control domains (meaning filter_cdoms is true, but filter_adapters and filter_domains are both false), vfio_ap_mdev_filter_matrix() is bypassed. Consequently, apm_filtered is passed to reset_queues_for_apids() with uninitialized stack garbage. This can cause reset_queues_for_apids() to interpret arbitrary stack garbage bits as valid APIDs to reset, potentially performing unintended guest hardware queue resets. Fix this by zero-initializing the apm_filtered bitmap at the beginning of vfio_ap_mdev_hot_plug_cfg() using bitmap_zero(). Fixes: eeb386aeb5b7c ("s390/vfio-ap: handle config changed and scan complete notification") Cc: stable@vger.kernel.org Signed-off-by: Anthony Krowiak Reviewed-by: Matthew Rosato --- drivers/s390/crypto/vfio_ap_ops.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c index 0f3537aadea8..d667ad4bbf70 100644 --- a/drivers/s390/crypto/vfio_ap_ops.c +++ b/drivers/s390/crypto/vfio_ap_ops.c @@ -2861,6 +2861,15 @@ static void vfio_ap_mdev_hot_plug_cfg(struct ap_matrix_mdev *matrix_mdev) DECLARE_BITMAP(apm_filtered, AP_DEVICES); bool filter_domains, filter_adapters, filter_cdoms, do_hotplug = false; + /* + * Zero out the apm_filtered bitmap in case there are no adapters or + * domains to be added, but only control domains. In that case, + * vfio_ap_mdev_filter_matrix() - which initializes apm_filtered - will + * not get called and the reset_queues_for_apids will crash because it + * will access an uninitialized bitmap. + */ + bitmap_zero(apm_filtered, AP_DEVICES); + filter_adapters = bitmap_intersects(matrix_mdev->matrix.apm, matrix_mdev->apm_add, AP_DEVICES); filter_domains = bitmap_intersects(matrix_mdev->matrix.aqm, -- 2.53.0