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Szmigiero" , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [PATCH v5 18/18] migration/multifd: Stop changing the packet on recv side In-Reply-To: References: <20240826195322.16532-1-farosas@suse.de> <20240826195322.16532-19-farosas@suse.de> Date: Mon, 26 Aug 2024 17:19:21 -0300 Message-ID: <8734mrxcja.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 51D0C1F8B5 X-Rspamd-Action: no action X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_BLOCKED(0.00)[rspamd.com]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; ARC_NA(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; FROM_HAS_DN(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; DWL_DNSWL_BLOCKED(0.00)[suse.de:dkim]; RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCPT_COUNT_THREE(0.00)[4]; MISSING_XM_UA(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[linaro.org:email, suse.de:dkim, suse.de:mid, suse.de:email, imap1.dmz-prg2.suse.org:rdns, imap1.dmz-prg2.suse.org:helo] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org Received-SPF: pass client-ip=195.135.223.131; envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 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, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: 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: > On Mon, Aug 26, 2024 at 04:53:22PM -0300, Fabiano Rosas wrote: >> As observed by Philippe, the multifd_ram_unfill_packet() function >> currently leaves the MultiFDPacket structure with mixed >> endianness. This is harmless, but ultimately not very clean. Aside >> from that, the packet is also written to on the recv side to ensure >> the ramblock name is null-terminated. >>=20 >> Stop touching the received packet and do the necessary work using >> stack variables instead. >>=20 >> While here tweak the error strings and fix the space before >> semicolons. Also remove the "100 times bigger" comment because it's >> just one possible explanation for a size mismatch and it doesn't even >> match the code. >>=20 >> CC: Philippe Mathieu-Daud=C3=A9 >> Signed-off-by: Fabiano Rosas >> --- >> migration/multifd-nocomp.c | 38 ++++++++++++++++---------------------- >> migration/multifd.c | 18 ++++++++---------- >> 2 files changed, 24 insertions(+), 32 deletions(-) >>=20 >> diff --git a/migration/multifd-nocomp.c b/migration/multifd-nocomp.c >> index f294d1b0b2..0cbf1b88e1 100644 >> --- a/migration/multifd-nocomp.c >> +++ b/migration/multifd-nocomp.c >> @@ -220,33 +220,29 @@ int multifd_ram_unfill_packet(MultiFDRecvParams *p= , Error **errp) >> MultiFDPacket_t *packet =3D p->packet; >> uint32_t page_count =3D multifd_ram_page_count(); >> uint32_t page_size =3D multifd_ram_page_size(); >> + uint32_t pages_per_packet =3D be32_to_cpu(packet->pages_alloc); >> + const char *ramblock_name; >> int i; >>=20=20 >> - packet->pages_alloc =3D be32_to_cpu(packet->pages_alloc); >> - /* >> - * If we received a packet that is 100 times bigger than expected >> - * just stop migration. It is a magic number. >> - */ >> - if (packet->pages_alloc > page_count) { >> - error_setg(errp, "multifd: received packet " >> - "with size %u and expected a size of %u", >> - packet->pages_alloc, page_count) ; >> + if (pages_per_packet > page_count) { >> + error_setg(errp, "multifd: received packet with %u pages, expec= ted %u", >> + pages_per_packet, page_count); >> return -1; >> } >>=20=20 >> p->normal_num =3D be32_to_cpu(packet->normal_pages); >> - if (p->normal_num > packet->pages_alloc) { >> - error_setg(errp, "multifd: received packet " >> - "with %u normal pages and expected maximum pages are= %u", >> - p->normal_num, packet->pages_alloc) ; >> + if (p->normal_num > pages_per_packet) { >> + error_setg(errp, "multifd: received packet with %u non-zero pag= es, " >> + "which exceeds maximum expected pages %u", >> + p->normal_num, pages_per_packet); >> return -1; >> } >>=20=20 >> p->zero_num =3D be32_to_cpu(packet->zero_pages); >> - if (p->zero_num > packet->pages_alloc - p->normal_num) { >> - error_setg(errp, "multifd: received packet " >> - "with %u zero pages and expected maximum zero pages = are %u", >> - p->zero_num, packet->pages_alloc - p->normal_num) ; >> + if (p->zero_num > pages_per_packet - p->normal_num) { >> + error_setg(errp, >> + "multifd: received packet with %u zero pages, expect= ed maximum %u", >> + p->zero_num, pages_per_packet - p->normal_num); >> return -1; >> } >>=20=20 >> @@ -254,12 +250,10 @@ int multifd_ram_unfill_packet(MultiFDRecvParams *p= , Error **errp) >> return 0; >> } >>=20=20 >> - /* make sure that ramblock is 0 terminated */ >> - packet->ramblock[255] =3D 0; >> - p->block =3D qemu_ram_block_by_name(packet->ramblock); >> + ramblock_name =3D g_strndup(packet->ramblock, 255); > > This one is leaked? > > IMHO the "temp var for endianess" is better justified than this specific > one, where I think always null-terminating the packet->ramblock[] doesn't > sound too bad - it makes sure all future ref to packet->ramblock is safe. Ok, I can drop this part. > >> + p->block =3D qemu_ram_block_by_name(ramblock_name); >> if (!p->block) { >> - error_setg(errp, "multifd: unknown ram block %s", >> - packet->ramblock); >> + error_setg(errp, "multifd: unknown ram block %s", ramblock_name= ); >> return -1; >> } >>=20=20 >> diff --git a/migration/multifd.c b/migration/multifd.c >> index b89715fdc2..256ecdea56 100644 >> --- a/migration/multifd.c >> +++ b/migration/multifd.c >> @@ -231,21 +231,19 @@ void multifd_send_fill_packet(MultiFDSendParams *p) >> static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **err= p) >> { >> MultiFDPacket_t *packet =3D p->packet; >> + uint32_t magic =3D be32_to_cpu(packet->magic); >> + uint32_t version =3D be32_to_cpu(packet->version); >> int ret =3D 0; >>=20=20 >> - packet->magic =3D be32_to_cpu(packet->magic); >> - if (packet->magic !=3D MULTIFD_MAGIC) { >> - error_setg(errp, "multifd: received packet " >> - "magic %x and expected magic %x", >> - packet->magic, MULTIFD_MAGIC); >> + if (magic !=3D MULTIFD_MAGIC) { >> + error_setg(errp, "multifd: received packet magic %x, expected %= x", >> + magic, MULTIFD_MAGIC); >> return -1; >> } >>=20=20 >> - packet->version =3D be32_to_cpu(packet->version); >> - if (packet->version !=3D MULTIFD_VERSION) { >> - error_setg(errp, "multifd: received packet " >> - "version %u and expected version %u", >> - packet->version, MULTIFD_VERSION); >> + if (version !=3D MULTIFD_VERSION) { >> + error_setg(errp, "multifd: received packet version %u, expected= %u", >> + version, MULTIFD_VERSION); >> return -1; >> } >>=20=20 >> --=20 >> 2.35.3 >>=20