Drivers: vmbus: Check for channel allocation before looking up relids

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: Drivers: vmbus: Check for channel allocation before looking up relids relid2channel() assumes vmbus channel array to be allocated when called. However, in cases such as kdump/kexec, not all relids will be reset by the host. When the second kernel boots and if the guest receives a vmbus interrupt during vmbus driver initialization before vmbus_connect() is called, before it finishes, or if it fails, the vmbus interrupt service routine is called which in turn calls relid2channel() and can cause a null pointer dereference. Print a warning and error out in relid2channel() for a channel id that's invalid in the second kernel.

References

• https://git.kernel.org/stable/c/176c6b4889195fbe7016d9401175b48c5c9edf68
• https://git.kernel.org/stable/c/c373e49fbb87aa177819866ed9194ebc5414dfd6
• https://git.kernel.org/stable/c/8c3f0ae5435fd20bb1e3a8308488aa6ac33151ee
• https://git.kernel.org/stable/c/a5c44f3446a0565139b7d8abc78f58b86c398123
• https://git.kernel.org/stable/c/1eb65c8687316c65140b48fad27133d583178e15