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Wed, 5 Aug 2026 11:05:14 +0000 (GMT) From: Christian Borntraeger To: KVM Cc: Christian Borntraeger , Janosch Frank , David Hildenbrand , linux-s390 , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Matthew Rosato , Douglas Freimuth Subject: [PATCH v3 8/8] KVM: s390: Fix length check __import_wp_info() Date: Wed, 5 Aug 2026 13:04:55 +0200 Message-ID: <20260805110455.7200-9-borntraeger@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260805110455.7200-1-borntraeger@linux.ibm.com> References: <20260805110455.7200-1-borntraeger@linux.ibm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 2hbGDGubmQqNExwQD3-XZ0hOFs0V-sc1 X-Proofpoint-Spam-Info: AW1haW4tMjYwODA1MDA4NiBTYWx0ZWRfX4Z4syrbTcfKE FgdocJ2VPVOt5XrSFPMvZI3USDEgrvQYVMNYvMo9pLANRFaa9i1D7yle8DzsEfO66VKQfrrEjVG 6jE5r435ZuuxJ7zi328Ae3RoWN3ULX8= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA1MDA4NiBTYWx0ZWRfX0EiHDRSDfngH 3NINjwwE7kvC0/otmDiNhcoKb6jNHDeqM85rObwCOHW8PSxGqNOEr663ExafRXaxNZouuqD2Y8n 4lll/zQIXgOp9M40jS4/W6LoHXFk36b94vmeJjOevfNQ3BYl9X5grnFoAGrjJixm/LO1R15tTmT jrO/4Au5WLQYxwsDCBCGCPnyFKV0McGuaVVirFB7rTSR2m1mDudwLqi3w2urq4b6bLWb1TrTzLF WWMjqKIwLOz1RxBaqqAB+jUpaaVGedpy82OGujlypMppbkg5w1uSpC777Eo7Z5pJ97mC0ZPeqTp fTWW3dfabp/hoSLKH86ph3yfKdbI0Dop9guvSJhD+ZJS/NiIIgTHb1hJpzO7KoHK1AZj4BDU7di 1Txuziapu1zjA6UQJLPyjZNy36XDhMi0sn8bQie5iK+0/MAKhUXqJMLjtqlPyfMphZ/0vIL+gpm bxhcj2fzD+CX2pHnF9Q== X-Proofpoint-GUID: 2hbGDGubmQqNExwQD3-XZ0hOFs0V-sc1 X-Authority-Analysis: v=2.4 cv=KfzidwYD c=1 sm=1 tr=0 ts=6a7318ee cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=Wui25AcxXJO4yD6ELYcA:9 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=2026-08-05_03,2026-08-04_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 suspectscore=0 malwarescore=0 adultscore=0 clxscore=1015 priorityscore=1501 phishscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608050086 struct kvm_hw_breakpoint::len is a __u64 that is fully controlled by user space. This is then assigned to wp_info->len, which is an int. The bounds check is done on the truncated value while the allocation uses the untruncated one: wp_info->len = bp_data->len; [...] if (wp_info->len < 0 || wp_info->len > MAX_WP_SIZE) return -EINVAL; wp_info->old_data = kmalloc(bp_data->len, GFP_KERNEL_ACCOUNT); Use the validated value for the allocation as intended. Without this fix userspace can trigger >4GB allocations which will fail and result in a WARN due to MAX_PAGE_ORDER. Fixes: 27291e2165b6 ("KVM: s390: hardware support for guest debugging") Cc: stable@vger.kernel.org Signed-off-by: Christian Borntraeger --- arch/s390/kvm/guestdbg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kvm/guestdbg.c b/arch/s390/kvm/guestdbg.c index f7c94d54efbe..9a6149e310bb 100644 --- a/arch/s390/kvm/guestdbg.c +++ b/arch/s390/kvm/guestdbg.c @@ -184,7 +184,7 @@ static int __import_wp_info(struct kvm_vcpu *vcpu, if (wp_info->len < 0 || wp_info->len > MAX_WP_SIZE) return -EINVAL; - wp_info->old_data = kmalloc(bp_data->len, GFP_KERNEL_ACCOUNT); + wp_info->old_data = kmalloc(wp_info->len, GFP_KERNEL_ACCOUNT); if (!wp_info->old_data) return -ENOMEM; /* try to backup the original value */ -- 2.53.0