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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: 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 Maydell writes: > On Wed, 4 Sept 2024 at 13:48, Fabiano Rosas wrote: >> >> In preparation for adding new payload types to multifd, move most of >> the no-compression code into multifd-nocomp.c. Let's try to keep a >> semblance of layering by not mixing general multifd control flow with >> the details of transmitting pages of ram. >> >> There are still some pieces leftover, namely the p->normal, p->zero, >> etc variables that we use for zero page tracking and the packet >> allocation which is heavily dependent on the ram code. >> >> Reviewed-by: Peter Xu >> Signed-off-by: Fabiano Rosas > > I know Coverity has only flagged this up because the > code has moved, but it seems like a good place to ask > the question: > >> +void multifd_ram_fill_packet(MultiFDSendParams *p) >> +{ >> + MultiFDPacket_t *packet = p->packet; >> + MultiFDPages_t *pages = &p->data->u.ram; >> + uint32_t zero_num = pages->num - pages->normal_num; >> + >> + packet->pages_alloc = cpu_to_be32(multifd_ram_page_count()); >> + packet->normal_pages = cpu_to_be32(pages->normal_num); >> + packet->zero_pages = cpu_to_be32(zero_num); >> + >> + if (pages->block) { >> + strncpy(packet->ramblock, pages->block->idstr, 256); > > Coverity points out that when we fill in the RAMBlock::idstr > here, if packet->ramblock is not NUL terminated then we won't > NUL-terminate idstr either (CID 1560071). > > Is this really what is intended? This is probably an oversight, although the migration destination truncates it before reading: /* make sure that ramblock is 0 terminated */ packet->ramblock[255] = 0; p->block = qemu_ram_block_by_name(packet->ramblock); If we ever start reading packet->ramblock on the source side in the future, then there might be a problem. > > Perhaps > pstrncpy(packet->ramblock, sizeof(packet->ramblock), > pages->block->idstr); > > would be better? Yep, thanks. I'll send a patch. > > (pstrncpy will always NUL-terminate, and won't pointlessly > zero-fill the space after the string in the destination.) > >> + } >> + >> + for (int i = 0; i < pages->num; i++) { >> + /* there are architectures where ram_addr_t is 32 bit */ >> + uint64_t temp = pages->offset[i]; >> + >> + packet->offset[i] = cpu_to_be64(temp); >> + } >> + >> + trace_multifd_send_ram_fill(p->id, pages->normal_num, >> + zero_num); >> +} > > thanks > -- PMM