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Tue, 14 Apr 2026 12:27:10 -0700 (PDT) X-Received: by 2002:a05:620a:17a3:b0:8b2:1ee9:dcfb with SMTP id af79cd13be357-8ddcce2b4eemr2826133285a.8.1776194829566; Tue, 14 Apr 2026 12:27:09 -0700 (PDT) Received: from x1.local ([142.189.10.167]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8ddb5f8886csm1121233485a.6.2026.04.14.12.27.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 12:27:08 -0700 (PDT) Date: Tue, 14 Apr 2026 15:27:00 -0400 From: Peter Xu To: Trieu Huynh Cc: qemu-devel@nongnu.org, Fabiano Rosas Subject: Re: [PATCH v2] migration: validate page_size in mapped-ram header before use Message-ID: References: <20260405094447.11347-1-viking4@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260405094447.11347-1-viking4@gmail.com> Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.54, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Sun, Apr 05, 2026 at 04:44:47PM +0700, Trieu Huynh wrote: > From: Trieu Huynh > > mapped_ram_read_header() reads page_size from the migration stream and > stores it in MappedRamHeader, but does not validate that the value is > non-zero before it is later used in parse_ramblock_mapped_ram(): > > num_pages = length / header.page_size; > > If a corrupted or malformed migration stream provides invalid, guest > resumes either with corrupted memory or crashes unexpectedly (eg. > page_size = 0) > > Add validation in mapped_ram_read_header() to reject invalid page_size > values early and return an error instead of continuing with an invalid > header. > > Steps to reproduce: > > Create a migration snapshot with mapped-ram enabled: > (qemu) migrate_set_capability mapped-ram on > (qemu) migrate file:/tmp/qemu-snapshots/snapshot.bin > Modify the snapshot so that MappedRamHeader.page_size becomes diff with > target psize. (0/512/8192/1GB). > Restore the snapshot: > (qemu) migrate_set_capability mapped-ram on > (qemu) migrate_incoming file:/tmp/qemu-snapshots/snapshot.bin > > As-is: > * [0]: Floating point exception (core dumped) > * [512/8192]: Silent corruption > * [1GB]: "post load hook failed for: kvm-tpr-opt" (EPERM) > To-be: > * All: qemu-system-x86_64: Migration mapped-ram header has invalid > page_size [val] (expected 4096) > > Signed-off-by: Trieu Huynh Reviewed-by: Peter Xu -- Peter Xu