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[SRU,Yakkety,Zesty,2/2] hv: don't reset hv_context.tsc_page on crash

Message ID 412af8ebea8dbf8f1c89e4c284bea577b3508364.1484950085.git.joseph.salisbury@canonical.com
State New
Headers show

Commit Message

Joseph Salisbury Jan. 27, 2017, 7:58 p.m. UTC 
From: Vitaly Kuznetsov <vkuznets@redhat.com>

BugLink: http://bugs.launchpad.net/bugs/1630924

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 56ef6718a1d8d77745033c5291e025ce18504159)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
---
 drivers/hv/hv.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
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Patch

diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index ab1f466..60db5ff 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -317,9 +317,10 @@  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
 }