CVE-2021-47554

In the Linux kernel, the following vulnerability has been resolved:

vdpa_sim: avoid putting an uninitialized iova_domain

The system will crash if we put an uninitialized iova_domain, this could happen when an error occurs before initializing the iova_domain in vdpasim_create().

BUG: kernel NULL pointer dereference, address: 0000000000000000 … RIP: 0010:__cpuhp_state_remove_instance+0x96/0x1c0 … Call Trace: put_iova_domain+0x29/0x220 vdpasim_free+0xd1/0x120 [vdpa_sim] vdpa_release_dev+0x21/0x40 [vdpa] device_release+0x33/0x90 kobject_release+0x63/0x160 vdpasim_create+0x127/0x2a0 [vdpa_sim] vdpasim_net_dev_add+0x7d/0xfe [vdpa_sim_net] vdpa_nl_cmd_dev_add_set_doit+0xe1/0x1a0 [vdpa] genl_family_rcv_msg_doit+0x112/0x140 genl_rcv_msg+0xdf/0x1d0 …

So we must make sure the iova_domain is already initialized before put it.

In addition, we may get the following warning in this case: WARNING: … drivers/iommu/iova.c:344 iova_cache_put+0x58/0x70

So we must make sure the iova_cache_put() is invoked only if the iova_cache_get() is already invoked. Lets fix it together.

Weakness

The product uses or accesses a resource that has not been initialized.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/bb93ce4b150dde79f58e34103cbd1fe829796649
• https://git.kernel.org/stable/c/e4d58ac67e63727aa45a4a26185876f598e8b3dd
• https://git.kernel.org/stable/c/bb93ce4b150dde79f58e34103cbd1fe829796649
• https://git.kernel.org/stable/c/e4d58ac67e63727aa45a4a26185876f598e8b3dd