[tip: x86/sev] x86/sev: Fix stack type check in vc_switch_off_ist()

[tip-bot2 for Joerg Roedel]

The following commit has been merged into the x86/sev branch of tip:

Commit-ID:     5681981fb788281b09a4ea14d310d30b2bd89132
Gitweb:        https://git.kernel.org/tip/5681981fb788281b09a4ea14d310d30b2bd89132
Author:        Joerg Roedel <jroedel@xxxxxxx>
AuthorDate:    Thu, 21 Oct 2021 10:08:32 +02:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Thu, 21 Oct 2021 18:24:44 +02:00

x86/sev: Fix stack type check in vc_switch_off_ist()

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@xxxxxxx>
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/20211021080833.30875-2-joro@xxxxxxxxxx
---
 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 a588009..f516f2b 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -709,7 +709,7 @@ 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: