[PATCH 5.14 487/849] x86/sev: Fix stack type check in vc_switch_off_ist()

Greg Kroah-Hartman
2021-11-15T23:06:10Z

From: Joerg Roedel <jroedel@suse.de>

[ Upstream commit 5681981fb788281b09a4ea14d310d30b2bd89132 ]

The value of STACK_TYPE_EXCEPTION_LAST points to the last _valid_
exception stack. Reflect that in the check done in the
vc_switch_off_ist() function.

Fixes: a13644f3a53de ("x86/entry/64: Add entry code for #VC handler")
Reported-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021080833.30875-2-joro@8bytes.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kernel/traps.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index cc6de3a01293c..5b1984d468227 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -743,7 +743,7 @@ asmlinkage __visible noinstr struct pt_regs *vc_switch_off_ist(struct pt_regs *r
stack = (unsigned long *)sp;

if (!get_stack_info_noinstr(stack, current, &info) || info.type == STACK_TYPE_ENTRY ||
- info.type >= STACK_TYPE_EXCEPTION_LAST)
+ info.type > STACK_TYPE_EXCEPTION_LAST)
sp = __this_cpu_ist_top_va(VC2);

sync:
--
2.33.0