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Tsirkin" , Jason Wang Cc: peter.maydell@linaro.org, lvivier@redhat.com, clg@redhat.com, Ani Sinha , qemu-devel@nongnu.org Subject: [PATCH] net/vhost-net: do not assert on null pointer return from tap_get_vhost_net() Date: Wed, 28 Jun 2023 16:58:04 +0530 Message-Id: <20230628112804.36676-1-anisinha@redhat.com> X-Mailer: git-send-email 2.39.1 MIME-Version: 1.0 Received-SPF: pass client-ip=170.10.133.124; envelope-from=anisinha@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, DKIMWL_WL_HIGH=-0.001, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org When 'vhost=off' or no vhost specific options at all are passed for the tap net-device backend, tap_get_vhost_net() can return NULL. The function net_init_tap_one() does not call vhost_net_init() on such cases and therefore vhost_net pointer within the tap device state structure remains NULL. Hence, assertion here on a NULL pointer return from tap_get_vhost_net() would not be correct. Remove it and fix the crash generated by qemu upon initialization in the following call chain : qdev_realize() -> pci_qdev_realize() -> virtio_device_realize() -> virtio_bus_device_plugged() -> virtio_net_get_features() -> get_vhost_net() fixes: 0e994668d00c9c ("vhost_net: add an assertion for TAP client backends") Signed-off-by: Ani Sinha Reviewed-by: Cédric Le Goater Tested-by: Cédric Le Goater --- hw/net/vhost_net.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c index 6db23ca323..6b958d6363 100644 --- a/hw/net/vhost_net.c +++ b/hw/net/vhost_net.c @@ -507,7 +507,12 @@ VHostNetState *get_vhost_net(NetClientState *nc) switch (nc->info->type) { case NET_CLIENT_DRIVER_TAP: vhost_net = tap_get_vhost_net(nc); - assert(vhost_net); + /* + * tap_get_vhost_net() can return NULL if a tap net-device backend is + * created with 'vhost=off' option, 'vhostforce=off' or no vhost or + * vhostforce or vhostfd options at all. Please see net_init_tap_one(). + * Hence, we omit the assertion here. + */ break; #ifdef CONFIG_VHOST_NET_USER case NET_CLIENT_DRIVER_VHOST_USER: