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([2001:b07:6468:f312:1142:70d6:6b9b:3cd1]) by smtp.gmail.com with ESMTPSA id t25sm3811506ejc.34.2020.06.30.22.49.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Jun 2020 22:49:41 -0700 (PDT) Subject: Re: [PATCH] pc: fix leak in pc_system_flash_cleanup_unused To: Alexander Bulekov , qemu-devel@nongnu.org References: <20200701015859.29820-1-alxndr@bu.edu> From: Paolo Bonzini Message-ID: Date: Wed, 1 Jul 2020 07:49:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200701015859.29820-1-alxndr@bu.edu> Content-Language: en-US Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.120; envelope-from=pbonzini@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/01 01:29:47 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Michael S. Tsirkin" , Eduardo Habkost , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 01/07/20 03:58, Alexander Bulekov wrote: > fix a leak detected when building with --enable-sanitizers: > ./i386-softmmu/qemu-system-i386 > Upon exit: > ==13576==ERROR: LeakSanitizer: detected memory leaks > > Direct leak of 1216 byte(s) in 1 object(s) allocated from: > #0 0x7f9d2ed5c628 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.5) > #1 0x7f9d2e963500 in g_malloc (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.) > #2 0x55fa646d25cc in object_new_with_type /tmp/qemu/qom/object.c:686 > #3 0x55fa63dbaa88 in qdev_new /tmp/qemu/hw/core/qdev.c:140 > #4 0x55fa638a533f in pc_pflash_create /tmp/qemu/hw/i386/pc_sysfw.c:88 > #5 0x55fa638a54c4 in pc_system_flash_create /tmp/qemu/hw/i386/pc_sysfw.c:106 > #6 0x55fa646caa1d in object_init_with_type /tmp/qemu/qom/object.c:369 > #7 0x55fa646d20b5 in object_initialize_with_type /tmp/qemu/qom/object.c:511 > #8 0x55fa646d2606 in object_new_with_type /tmp/qemu/qom/object.c:687 > #9 0x55fa639431e9 in qemu_init /tmp/qemu/softmmu/vl.c:3878 > #10 0x55fa6335c1b8 in main /tmp/qemu/softmmu/main.c:48 > #11 0x7f9d2cf06e0a in __libc_start_main ../csu/libc-start.c:308 > #12 0x55fa6335f8e9 in _start (/tmp/qemu/build/i386-softmmu/qemu-system-i386) > > Signed-off-by: Alexander Bulekov > --- > > I am not very familiar with the QOM, so maybe this isn't the right way > of going about this. With the call to object_property_add_child in > pc_sysfw.c:pc_pflash_create, object_ref is called on the pflash device. > In the pc_system_flash_cleanup_unused function, there are calls to > object_propery_del and object_unparent, but it seems neither of these > calls object_unref. So do we need to manually decrement the refcount? Yes; you can also add it in pc_pflash_create, because /* * Since object_property_add_child added a reference to the child object, * we can drop the reference added by object_initialize(), so the child * property will own the only reference to the object. */ (from object_initialize_childv). Paolo > hw/i386/pc_sysfw.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c > index ec2a3b3e7e..f69a93671a 100644 > --- a/hw/i386/pc_sysfw.c > +++ b/hw/i386/pc_sysfw.c > @@ -123,6 +123,7 @@ static void pc_system_flash_cleanup_unused(PCMachineState *pcms) > object_property_del(OBJECT(pcms), prop_name); > g_free(prop_name); > object_unparent(dev_obj); > + object_unref(dev_obj); > pcms->flash[i] = NULL; > } > } >