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

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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: 04df7ac399 ("Drivers: hv: Introduce per-cpu event ring tail")
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Link: https://lore.kernel.org/r/20250421163134.2024-1-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250421163134.2024-1-mhklinux@outlook.com>
This commit is contained in:
Michael Kelley
2025-04-25 21:13:53 +00:00
committed by Wei Liu
parent 9bbb8a07fd
commit 14ae3003e7
1 changed files with 5 additions and 3 deletions
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drivers/hv/hv_common.c
+5 -3
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@@ -566,9 +566,11 @@ int hv_common_cpu_die(unsigned int cpu)
* originally allocated memory is reused in hv_common_cpu_init().
*/
synic_eventring_tail = this_cpu_ptr(hv_synic_eventring_tail);
kfree(*synic_eventring_tail);
*synic_eventring_tail = NULL;
if (hv_root_partition()) {
synic_eventring_tail = this_cpu_ptr(hv_synic_eventring_tail);
kfree(*synic_eventring_tail);
*synic_eventring_tail = NULL;
}
return 0;
}