From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7B1E9F01832 for ; Fri, 6 Mar 2026 13:46:42 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vyVVW-0000LK-S5; Fri, 06 Mar 2026 08:46:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vyVVU-0000Ki-Eb for qemu-devel@nongnu.org; Fri, 06 Mar 2026 08:46:20 -0500 Received: from smtp-out1.suse.de ([2a07:de40:b251:101:10:150:64:1]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1vyVVS-0006qw-O9 for qemu-devel@nongnu.org; Fri, 06 Mar 2026 08:46:20 -0500 Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (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 smtp-out1.suse.de (Postfix) with ESMTPS id 916933E7B4; Fri, 6 Mar 2026 13:46:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1772804776; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=vCGIMwX0POlyXSSo0cPbr34QQ/IDgZQl4nDpVnfGka0=; b=WFGt3oUYt9bGnksQfYyYhtmR/XCno9rKgcn53xKrjailNDKRgu+3vM0F2kTWA04oWa39w8 oeojs5eatp02+CSP58aZ+8kM+lby7L326+px+rKeSs5DULfDCmpAYWLXnUqA2jrnhtqayT gs5+ojIrYofBCel+aa8RBy+0GNvFFy4= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1772804776; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=vCGIMwX0POlyXSSo0cPbr34QQ/IDgZQl4nDpVnfGka0=; b=jTac2mcqX7G2nqYQESJVN9YBefAgOsByV9DeCjjjKChBlnWf8znVA/JBXho6iJdMpZVYVf zDqS39iGjU0cN2Bg== Authentication-Results: smtp-out1.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1772804776; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=vCGIMwX0POlyXSSo0cPbr34QQ/IDgZQl4nDpVnfGka0=; b=WFGt3oUYt9bGnksQfYyYhtmR/XCno9rKgcn53xKrjailNDKRgu+3vM0F2kTWA04oWa39w8 oeojs5eatp02+CSP58aZ+8kM+lby7L326+px+rKeSs5DULfDCmpAYWLXnUqA2jrnhtqayT gs5+ojIrYofBCel+aa8RBy+0GNvFFy4= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1772804776; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=vCGIMwX0POlyXSSo0cPbr34QQ/IDgZQl4nDpVnfGka0=; b=jTac2mcqX7G2nqYQESJVN9YBefAgOsByV9DeCjjjKChBlnWf8znVA/JBXho6iJdMpZVYVf zDqS39iGjU0cN2Bg== 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 18B9A3EA75; Fri, 6 Mar 2026 13:46:15 +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 MF+fM6faqmlzDwAAD6G6ig (envelope-from ); Fri, 06 Mar 2026 13:46:15 +0000 From: Fabiano Rosas To: Alexandr Moshkov , qemu-devel@nongnu.org Cc: "yc-core@yandex-team.ru" , Peter Xu , Alexandr Moshkov Subject: Re: [PATCH v2] vmstate: fix subsection load name check In-Reply-To: <20260302070626.613396-1-dtalexundeer@yandex-team.ru> References: <20260302070626.613396-1-dtalexundeer@yandex-team.ru> Date: Fri, 06 Mar 2026 10:46:13 -0300 Message-ID: <87y0k5136i.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TO_DN_EQ_ADDR_SOME(0.00)[]; MISSING_XM_UA(0.00)[]; RCVD_TLS_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_COUNT_TWO(0.00)[2]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,imap1.dmz-prg2.suse.org:helo] Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:1; envelope-from=farosas@suse.de; helo=smtp-out1.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 Alexandr Moshkov writes: > When loading a subset, its name is checked for the parent prefix. The > following bug may occur here: > > Let's say there is a vmstate named "virtio-blk", it has a subsection > named "virtio-blk/subsection", and it also has another vmstate named > "virtio" in the fields. > Then, during the migration, when trying to load this subsection for > "virtio", the prefix condition will pass for "virtio-blk/subsection" and > then the migration will break, because this vmstate does not have such a > subsection. > > In other words, if a field inside vmstate1 is set via vmstate2 with a > name that is a prefix of the parent vmstate, then the field can "steal" > a subsection belonging to the parent state. > > Looks like it happens because migration stream for "virtio-blk" looks > like this: > > [virtio-blk header] [virtio-blk fields] [virtio-blk subsections] > > "virtio-blk" contains "virtio" field, so migration stream is: > > [virtio-blk header] [virtio header] [virtio fields] [virtio > subsections] [virtio-blk subsections] > > And when we load the subsections of the "virtio" device, > vmstate_subsection_load() uses qemu_peek_byte() to try to figure out if > this is his subsection. This is where we encounter an error. > > Thus, the error occurs due to the fact that vmsd does not know how many > subsections it has when loading (this does not appear anywhere in the > migration stream), so it tries to load all the appropriate ones by > names. > > Fix it by checking `/` at the end of idstr. > > Signed-off-by: Alexandr Moshkov > --- > migration/vmstate.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/migration/vmstate.c b/migration/vmstate.c > index 4d28364f7b..187f3861f2 100644 > --- a/migration/vmstate.c > +++ b/migration/vmstate.c > @@ -613,7 +613,7 @@ static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd, > > while (qemu_peek_byte(f, 0) == QEMU_VM_SUBSECTION) { > char idstr[256], *idstr_ret; > - int ret; > + int ret, vmsd_name_len; > uint8_t version_id, len, size; > const VMStateDescription *sub_vmsd; > > @@ -631,7 +631,10 @@ static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd, > memcpy(idstr, idstr_ret, size); > idstr[size] = 0; > > - if (strncmp(vmsd->name, idstr, strlen(vmsd->name)) != 0) { > + vmsd_name_len = strlen(vmsd->name); > + if (strncmp(vmsd->name, idstr, vmsd_name_len) != 0 || > + /* to avoid taking parent subsection here */ > + idstr[vmsd_name_len] != '/') { > trace_vmstate_subsection_load_bad(vmsd->name, idstr, "(prefix)"); > /* it doesn't have a valid subsection name */ > return 0; Hi, this breaks migration for s390x and ppc64: qemu-system-s390x: Missing section footer for qemu-s390-flic qemu-system-ppc64: Missing section footer for spapr_iommu