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bh=yWFEqYBzV6vSmyx5QuCiJrafX/4t8frvImO28PzBlEk=; b=RiBPDGJFtePTm5g3p54ftyHDrJvk3KBfS0MELUGFMPOuM4BOQrvE6viJ4ORlT6mf59JtL9 JWKhLJIMU24D5LCw== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 11758779B1; Tue, 28 Jul 2026 19:44:27 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id qWG5NJsGaWqDQwAAD6G6ig (envelope-from ); Tue, 28 Jul 2026 19:44:27 +0000 From: Fabiano Rosas To: Peter Xu , qemu-devel@nongnu.org Cc: peterx@redhat.com, Juraj Marcin , xlabai , Jules Denardou , Tristan Madani , qemu-stable Subject: Re: [PATCH 2/5] migration/multifd: Validate next_packet_size in zlib/zstd recv In-Reply-To: <20260728155247.1894355-3-peterx@redhat.com> References: <20260728155247.1894355-1-peterx@redhat.com> <20260728155247.1894355-3-peterx@redhat.com> Date: Tue, 28 Jul 2026 16:44:21 -0300 Message-ID: <87wlueoq5m.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Action: no action X-Rspamd-Queue-Id: 791333E08 X-Spamd-Result: default: False [-4.51 / 50.00]; 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envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=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 Peter Xu writes: > The zlib and zstd multifd compression backends read next_packet_size from > the incoming migration stream and use it directly as the read length into a > fixed-size buffer (MULTIFD_PACKET_SIZE * 2 = 1MB). A malicious migration > source can set next_packet_size bigger than allocated, causing a heap > buffer overflow write on the destination. > > Add a check against zbuff_len before reading, matching what the qatzip > backend already does. Also replace the assert(in_size == 0) for empty > packets with proper error reporting, since the value is wire-controlled, > meanwhile assert() stops working with release builds. > > Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3737 > Reported-by: xlabai > Reported-by: Jules Denardou > Reported-by: Tristan Madani > Reported-by: david korczynski (@david1766) > Reported-by: huntr bubble (@bubblehuntr) > Cc: qemu-stable > Cc: Fabiano Rosas > Signed-off-by: Peter Xu Reviewed-by: Fabiano Rosas