CVE-2026-99216Drivers: hv: Don't reset VMBus connection state on error/exit paths

Official description

In the Linux kernel, the following vulnerability has been resolved: Drivers: hv: Don't reset VMBus connection state on error/exit paths In two places, current code forces vmbus_connection.conn_state to DISCONNECTED prior to calling vmbus_disconnect(). But vmbus_disconnect() calls vmbus_initiate_unload(), which unloads the VMBus connection only if the conn_state is CONNECTED. Consequently, the connection remains and the Hyper-V host might continue to send messages or post VMBus interrupts. The problem was introduced in commit 74347a99e73ae ("x86/Hyper-V: Unload vmbus channel in hv panic callback"), in that vmbus_initiate_unload() started checking the current connection state before doing the unload. This commit removed some occurrences where conn_state was forced to DISCONNECTED, but these two remained, apparently due to an oversight at the time. Fix this by not forcing conn_state to DISCONNECTED during VMBus exit, or if a failure occurs when establishing the connection in the first place. Whatever value conn_state has at the time is then read by vmbus_initiate_unload() to determine if there is a connection to be unloaded.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/2939215d57bc8e4189290544fca78f3809ac3ef8
• https://git.kernel.org/stable/c/a0ae955ba9a5067a157ebb8defb4a0a9cb1fc304
• https://git.kernel.org/stable/c/deef3ab5129ae4c45662c957cdab3739eb047fb1
• https://git.kernel.org/stable/c/2e5ffbf1e41abbf6e02ce28115107938f55ff646
• https://git.kernel.org/stable/c/2732210132f92aca0622b5134027990a809279d5
• https://git.kernel.org/stable/c/f47ce27af80b87cc684d5c12b65506af498ac7e5
• https://git.kernel.org/stable/c/3195546a377c2d8d176d837e8baad5ce15d11195
• https://git.kernel.org/stable/c/ec31dc39e835ccde0930daccece8c492d28282fc