Commit 14ae3003 authored by Michael Kelley's avatar Michael Kelley Committed by Wei Liu
Browse files

Drivers: hv: Fix bad ref to hv_synic_eventring_tail when CPU goes offline 



When a CPU goes offline, hv_common_cpu_die() frees the
hv_synic_eventring_tail memory for the CPU. But in a normal VM (i.e., not
running in the root partition) the per-CPU memory has not been allocated,
resulting in a bad memory reference and oops when computing the argument
to kfree().

Fix this by freeing the memory only when running in the root partition.

Fixes: 04df7ac3 ("Drivers: hv: Introduce per-cpu event ring tail")
Signed-off-by: default avatarMichael Kelley <mhklinux@outlook.com>
Reviewed-by: default avatarNuno Das Neves <nunodasneves@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250421163134.2024-1-mhklinux@outlook.com


Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
Message-ID: <20250421163134.2024-1-mhklinux@outlook.com>
parent 9bbb8a07

drivers/hv/hv_common.c

+5 −3
Original line number Diff line number Diff line
@@ -566,9 +566,11 @@ int hv_common_cpu_die(unsigned int cpu) 
	 * originally allocated memory is reused in hv_common_cpu_init().

	 */



	if (hv_root_partition()) {

		synic_eventring_tail = this_cpu_ptr(hv_synic_eventring_tail);

		kfree(*synic_eventring_tail);

		*synic_eventring_tail = NULL;

	}



	return 0;

}