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From:   Joerg Roedel <joro@8bytes.org>
To:     x86@kernel.org
Cc:     Joerg Roedel <joro@8bytes.org>, Joerg Roedel <jroedel@suse.de>,
        Tom Lendacky <thomas.lendacky@amd.com>, hpa@zytor.com,
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        Erdem Aktas <erdemaktas@google.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
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        Martin Radev <martin.b.radev@gmail.com>,
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Subject: [PATCH 1/2] x86/sev: Fix stack type check in vc_switch_off_ist()
Date:   Thu, 21 Oct 2021 10:08:32 +0200
Message-Id: <20211021080833.30875-2-joro@8bytes.org>
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From: Joerg Roedel <jroedel@suse.de>

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.

Reported-by: Tom Lendacky <thomas.lendacky@amd.com>
Fixes: a13644f3a53de ("x86/entry/64: Add entry code for #VC handler")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 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 a58800973aed..f516f2b4797e 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:
-- 
2.33.1