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[79.181.55.232]) by smtp.gmail.com with ESMTPSA id p16sm6559256wru.27.2020.06.09.21.27.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jun 2020 21:27:50 -0700 (PDT) Date: Wed, 10 Jun 2020 00:27:48 -0400 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org Subject: [PULL 34/56] char-socket: return -1 in case of disconnect during tcp_chr_write Message-ID: <20200610042613.1459309-35-mst@redhat.com> References: <20200610042613.1459309-1-mst@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200610042613.1459309-1-mst@redhat.com> X-Mailer: git-send-email 2.24.1.751.gd10ce2899c X-Mutt-Fcc: =sent X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=mst@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/09 23:51:15 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_H4=-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: Peter Maydell , Paolo Bonzini , Dima Stepanov , =?utf-8?q?Marc-Andr=C3=A9?= Lureau Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Dima Stepanov During testing of the vhost-user-blk reconnect functionality the qemu SIGSEGV was triggered: start qemu as: x86_64-softmmu/qemu-system-x86_64 -m 1024M -M q35 \ -object memory-backend-file,id=ram-node0,size=1024M,mem-path=/dev/shm/qemu,share=on \ -numa node,cpus=0,memdev=ram-node0 \ -chardev socket,id=chardev0,path=./vhost.sock,noserver,reconnect=1 \ -device vhost-user-blk-pci,chardev=chardev0,num-queues=4 --enable-kvm start vhost-user-blk daemon: ./vhost-user-blk -s ./vhost.sock -b test-img.raw If vhost-user-blk will be killed during the vhost initialization process, for instance after getting VHOST_SET_VRING_CALL command, then QEMU will fail with the following backtrace: Thread 1 "qemu-system-x86" received signal SIGSEGV, Segmentation fault. 0x00005555559272bb in vhost_user_read (dev=0x7fffef2d53e0, msg=0x7fffffffd5b0) at ./hw/virtio/vhost-user.c:260 260 CharBackend *chr = u->user->chr; #0 0x00005555559272bb in vhost_user_read (dev=0x7fffef2d53e0, msg=0x7fffffffd5b0) at ./hw/virtio/vhost-user.c:260 #1 0x000055555592acb8 in vhost_user_get_config (dev=0x7fffef2d53e0, config=0x7fffef2d5394 "", config_len=60) at ./hw/virtio/vhost-user.c:1645 #2 0x0000555555925525 in vhost_dev_get_config (hdev=0x7fffef2d53e0, config=0x7fffef2d5394 "", config_len=60) at ./hw/virtio/vhost.c:1490 #3 0x00005555558cc46b in vhost_user_blk_device_realize (dev=0x7fffef2d51a0, errp=0x7fffffffd8f0) at ./hw/block/vhost-user-blk.c:429 #4 0x0000555555920090 in virtio_device_realize (dev=0x7fffef2d51a0, errp=0x7fffffffd948) at ./hw/virtio/virtio.c:3615 #5 0x0000555555a9779c in device_set_realized (obj=0x7fffef2d51a0, value=true, errp=0x7fffffffdb88) at ./hw/core/qdev.c:891 ... The problem is that vhost_user_write doesn't get an error after disconnect and try to call vhost_user_read(). The tcp_chr_write() routine should return -1 in case of disconnect. Indicate the EIO error if this routine is called in the disconnected state. Signed-off-by: Dima Stepanov Reviewed-by: Marc-André Lureau Message-Id: Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- chardev/char-socket.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/chardev/char-socket.c b/chardev/char-socket.c index db253d4024..18e762643b 100644 --- a/chardev/char-socket.c +++ b/chardev/char-socket.c @@ -175,15 +175,16 @@ static int tcp_chr_write(Chardev *chr, const uint8_t *buf, int len) if (ret < 0 && errno != EAGAIN) { if (tcp_chr_read_poll(chr) <= 0) { + /* Perform disconnect and return error. */ tcp_chr_disconnect_locked(chr); - return len; } /* else let the read handler finish it properly */ } return ret; } else { - /* XXX: indicate an error ? */ - return len; + /* Indicate an error. */ + errno = EIO; + return -1; } }