CVE-2021-47554

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> vdpa_sim: avoid putting an uninitialized iova_domain<br /> <br /> The system will crash if we put an uninitialized iova_domain, this<br /> could happen when an error occurs before initializing the iova_domain<br /> in vdpasim_create().<br /> <br /> BUG: kernel NULL pointer dereference, address: 0000000000000000<br /> ...<br /> RIP: 0010:__cpuhp_state_remove_instance+0x96/0x1c0<br /> ...<br /> Call Trace:<br /> <br /> put_iova_domain+0x29/0x220<br /> vdpasim_free+0xd1/0x120 [vdpa_sim]<br /> vdpa_release_dev+0x21/0x40 [vdpa]<br /> device_release+0x33/0x90<br /> kobject_release+0x63/0x160<br /> vdpasim_create+0x127/0x2a0 [vdpa_sim]<br /> vdpasim_net_dev_add+0x7d/0xfe [vdpa_sim_net]<br /> vdpa_nl_cmd_dev_add_set_doit+0xe1/0x1a0 [vdpa]<br /> genl_family_rcv_msg_doit+0x112/0x140<br /> genl_rcv_msg+0xdf/0x1d0<br /> ...<br /> <br /> So we must make sure the iova_domain is already initialized before<br /> put it.<br /> <br /> In addition, we may get the following warning in this case:<br /> WARNING: ... drivers/iommu/iova.c:344 iova_cache_put+0x58/0x70<br /> <br /> So we must make sure the iova_cache_put() is invoked only if the<br /> iova_cache_get() is already invoked. Let&amp;#39;s fix it together.