[PATCH 4.9 110/153] hv: dont reset hv_context.tsc_page on crash

Greg Kroah-Hartman
2017-03-10T09:23:22Z

From: Vitaly Kuznetsov <vkuznets@redhat.com>

commit 56ef6718a1d8d77745033c5291e025ce18504159 upstream.

It may happen that secondary CPUs are still alive and resetting
hv_context.tsc_page will cause a consequent crash in read_hv_clock_tsc()
as we don't check for it being not NULL there. It is safe as we're not
freeing this page anyways.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hv/hv.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -309,9 +309,10 @@ void hv_cleanup(bool crash)

hypercall_msr.as_uint64 = 0;
wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
- if (!crash)
+ if (!crash) {
vfree(hv_context.tsc_page);
- hv_context.tsc_page = NULL;
+ hv_context.tsc_page = NULL;
+ }
}
#endif
}