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Tue, 4 Aug 2026 17:19:29 +0000 (GMT) Message-ID: Date: Tue, 4 Aug 2026 13:19:29 -0400 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 5/7] KVM: s390: Fix old_data leak in guest debug error path To: Christian Borntraeger , KVM Cc: Janosch Frank , David Hildenbrand , linux-s390 , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Douglas Freimuth References: <20260804162435.28617-1-borntraeger@linux.ibm.com> <20260804162435.28617-6-borntraeger@linux.ibm.com> Content-Language: en-US From: Matthew Rosato In-Reply-To: <20260804162435.28617-6-borntraeger@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA0MDE0MCBTYWx0ZWRfX4rpMTS11RsPl +4e7+rrji9xYhIVeEgiis7LS6AhqUSMU0zMEWTZ1oXCNejZOVWbugRXeaq8LLI3EQTjX94DGNj4 PJcVCLBDU4h6Wh5g+7OTFlgtAVfxEmzV2lTFJogXpcw2+33LVeKR3FdHVV7wd96YPluZb2ao8uI d7Z4OOL23j8V0RFa8aIfodwATeGKnWGYBUUtMi9vGXgMKHawrvI8QHlo7kWTrVSq1JipfN3Vrn1 YzeSSci5C7i6UN2itBfeAMj8vwtL9y8rpf2f148ewizmt8jTXBxQJN/w9sn/y2FJGIj8QmzGC+T uGAePRjofT4J7Y+2Cpf8SeYBTLJpyUC0cZNh6Bv7HI/96nPDogmHG3EtkiTxA6YdDWSEdem7Lc4 mGaI29NgPr0L/Xbh2LeO9mBbj0z4HmUd7F90vRyqITqtqnhhMmgzU4LsNSdN8NMMDV6QjbdI1mU v+xUUtUmAiXyVUK3Dwg== X-Authority-Analysis: v=2.4 cv=WIFPmHsR c=1 sm=1 tr=0 ts=6a721f26 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=E40_yC0fcIR57zUHXlQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: p2liktxqoHo3VrA5_rVj571c4emKmdIM X-Proofpoint-ORIG-GUID: p2liktxqoHo3VrA5_rVj571c4emKmdIM X-Proofpoint-Spam-Info: AW1haW4tMjYwODA0MDE0MCBTYWx0ZWRfX1IdepmyL8yNe uFOljU5rhdHbxBnh6ImzvsaUk7NeqUQdcsX6SqPi5vFZ68lqLGGXtbEFAPbwA9UGVCVCliZoUQs V/WiPkjDxbLhECfHSosGALlmwCDwwR8= 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=2026-08-04_03,2026-08-04_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 malwarescore=0 suspectscore=0 clxscore=1015 impostorscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608040140 On 8/4/26 12:24 PM, Christian Borntraeger wrote: > __import_wp_info() allocates a per-watchpoint old_data buffer to back up > the original guest memory contents. If a later watchpoint of the same > KVM_SET_GUEST_DEBUG request fails to import, kvm_s390_import_bp_data() > jumps to the error label, which frees the wp_info array but not the > old_data buffers of the entries that were imported successfully. Up to > MAX_BP_COUNT - 1 buffers of up to MAX_WP_SIZE bytes are leaked per failed > request, and the request can be repeated. > > Create error handling for cleaning up all created old_data memory > areas. > > Fixes: 27291e2165b6 ("KVM: s390: hardware support for guest debugging") > Cc: stable@vger.kernel.org > Signed-off-by: Christian Borntraeger Reviewed-by: Matthew Rosato > --- > arch/s390/kvm/guestdbg.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/s390/kvm/guestdbg.c b/arch/s390/kvm/guestdbg.c > index 4c02dbebb2eb..f7c94d54efbe 100644 > --- a/arch/s390/kvm/guestdbg.c > +++ b/arch/s390/kvm/guestdbg.c > @@ -252,7 +252,7 @@ int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu, > ret = __import_wp_info(vcpu, &bp_data[i], > &wp_info[nr_wp]); > if (ret) > - goto error; > + goto error_wp; > nr_wp++; > break; > case KVM_HW_BP: > @@ -269,6 +269,10 @@ int kvm_s390_import_bp_data(struct kvm_vcpu *vcpu, > vcpu->arch.guestdbg.hw_wp_info = wp_info; > kfree(bp_data); > return 0; > + > +error_wp: > + while (nr_wp--) > + kfree(wp_info[nr_wp].old_data); > error: > kfree(bp_data); > kfree(wp_info);