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Fri, 19 Jan 2024 23:43:53 +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 7qQRETkJq2WEVQAAD6G6ig (envelope-from ); Fri, 19 Jan 2024 23:43:53 +0000 From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: Peter Xu Subject: Re: [PATCH 1/5] migration: Fix use-after-free of migration state object In-Reply-To: <20240119233922.32588-2-farosas@suse.de> References: <20240119233922.32588-1-farosas@suse.de> <20240119233922.32588-2-farosas@suse.de> Date: Fri, 19 Jan 2024 20:43:50 -0300 Message-ID: <87ttn8vqh5.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain Authentication-Results: smtp-out2.suse.de; none X-Spamd-Result: default: False [-1.42 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; BAYES_HAM(-0.12)[67.11%]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; RCPT_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[] Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:2; 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 Fabiano Rosas writes: > We're currently allowing the process_incoming_migration_bh bottom-half > to run without holding a reference to the 'current_migration' object, > which leads to a segmentation fault if the BH is still live after > migration_shutdown() has dropped the last reference to > current_migration. > > In my system the bug manifests as migrate_multifd() returning true > when it shouldn't and multifd_load_shutdown() calling > multifd_recv_terminate_threads() which crashes due to an uninitialized > multifd_recv_state. > > Fix the issue by holding a reference to the object when scheduling the > BH and dropping it before returning from the BH. The same is already > done for the cleanup_bh at migrate_fd_cleanup_schedule(). > > Signed-off-by: Fabiano Rosas Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1969