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envelope-from=dimastep@yandex-team.ru; helo=forwardcorp1j.mail.yandex.net X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/30 09:36:59 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 5.45.199.163 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fam@euphon.net, kwolf@redhat.com, yc-core@yandex-team.ru, qemu-block@nongnu.org, mst@redhat.com, jasowang@redhat.com, dgilbert@redhat.com, mreitz@redhat.com, arei.gonglei@huawei.com, fengli@smartx.com, stefanha@redhat.com, marcandre.lureau@redhat.com, pbonzini@redhat.com, raphael.norwitz@nutanix.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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 --- chardev/char-socket.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/chardev/char-socket.c b/chardev/char-socket.c index 185fe38..c128cca 100644 --- a/chardev/char-socket.c +++ b/chardev/char-socket.c @@ -175,14 +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) { tcp_chr_disconnect_locked(chr); - return len; + /* Return an error since we made a disconnect. */ + return ret; } /* else let the read handler finish it properly */ } return ret; } else { - /* XXX: indicate an error ? */ - return len; + /* Indicate an error. */ + errno = EIO; + return -1; } } -- 2.7.4