CVE-2021-47060 Information

Description

In the Linux kernel the following vulnerability has been resolved:

KVM: Stop looking for coalesced MMIO zones if the bus is destroyed

Abort the walk of coalesced MMIO zones if kvm_io_bus_unregister_dev() fails to allocate memory for the new instance of the bus. If it can’t instantiate a new bus unregister_dev() destroys all devices except the target device. But it doesn’t tell the caller that it obliterated the bus and invoked the destructor for all devices that were on the bus. In the coalesced MMIO case this can result in a deleted list entry dereference due to attempting to continue iterating on coalesced_zones after future entries (in the walk) have been deleted.

Opportunistically add curly braces to the for-loop which encompasses many lines but sneaks by without braces due to the guts being a single if statement.

Reference

https://git.kernel.org/stable/c/7d1bc32d6477ff96a32695ea4be8144e4513ab2d https://git.kernel.org/stable/c/2a20592baff59c5351c5200ec667e1a2aa22af85 https://git.kernel.org/stable/c/168e82f640ed1891a700bdb43e37da354b2ab63c https://git.kernel.org/stable/c/50cbad42bfea8c052b7ca590bd4126cdc898713c https://git.kernel.org/stable/c/5d3c4c79384af06e3c8e25b7770b6247496b4417 In the Linux kernel the following vulnerability has been resolved:

KVM: Stop looking for coalesced MMIO zones if the bus is destroyed

Abort the walk of coalesced MMIO zones if kvm_io_bus_unregister_dev() fails to allocate memory for the new instance of the bus.

If it can’t instantiate a new bus unregister_dev() destroys all devices except the target device.

But it doesn’t tell the caller that it obliterated the bus and invoked the destructor for all devices that were on the bus.

In the coalesced MMIO case this can result in a deleted list entry dereference due to attempting to continue iterating on coalesced_zones after future entries (in the walk) have been deleted.

Opportunistically add curly braces to the for-loop which encompasses many lines but sneaks by without braces due to the guts being a single if statement.