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Wed, 12 Aug 2026 17:09:53 +0000 (GMT) Received: from li-4c4c4544-004d-4810-8043-b7c04f423534.ibm.com.com (unknown [9.61.9.29]) by smtpav06.dal12v.mail.ibm.com (Postfix) with ESMTP; Wed, 12 Aug 2026 17:09:53 +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 v4 6/9] s390/vfio-ap: fix potential use of uninitialized apm_filtered bitmap Date: Wed, 12 Aug 2026 13:09:42 -0400 Message-ID: <20260812170945.738351-7-akrowiak@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260812170945.738351-1-akrowiak@linux.ibm.com> References: <20260812170945.738351-1-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-Authority-Analysis: v=2.4 cv=RsP16imK c=1 sm=1 tr=0 ts=6a7ca8e4 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=bGM9o4fjUnjFpbELYA8A:9 X-Proofpoint-GUID: 72qeSOPsRckPQxYCeCMzlZWaGdQ_-aXP X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEyMDEzOCBTYWx0ZWRfXz/qxE4UKmxXd 7uKBpdKMCxCu+ReNZ6gtLcV5Yr9dkW9M8se5b38JcqCO0EkYKz9o1+B3yimeJsUl+DaOCvtB4M0 P+EfwOftm0DWQK0yirHaMhq/5eOQ3szA7Do7LbH60ysufhz9TYouwcPavI6c/e8DX1tvj96T2cF NHNkWJNFvJPCseEWT+HOYdQbotAuDDIBYnF7L2s9CERqTm8ZRnTgVFb5UbCS5ooIOqyP9mhdXlY RyPFJIeKnca4RGSN5PbxKX/3bRyFjo9HeLqwHKTVqRl4ZavAkm4cDqbqpU+Geq8FsqIEGtjfZw5 D0FmAEbHFo0AgOnMlFxqVLE1A0T/Rxsz4bLptAUi9jOOSB4DLNDK7yANSFGfsh8srHikOhvr7qH bLLt6x8Ww8hdPivmOO4s15v1xjRzD9x2cr/eEfmISMHluUE6Q+cLNzUmujtZjFrzWiO8/kh4ORR ELNnrVd0iERVfU4mSQg== X-Proofpoint-ORIG-GUID: 72qeSOPsRckPQxYCeCMzlZWaGdQ_-aXP X-Proofpoint-Spam-Info: AW1haW4tMjYwODEyMDEzOCBTYWx0ZWRfX0nf5iTVX8fCV ZnqWSzb4eT1rP6gTwbG3Wv/0/Ft95BElBFFHXlYG1xYm2mVIyp8jx4M8uoKr3TeZSb5r+iXUrsv jgfDEhphw0pV9FI6p8eeTYAxI8xvPOE= 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_05,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 suspectscore=0 clxscore=1015 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608120138 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