From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Tom Lendacky <thomas.lendacky@amd.com>,
        Joerg Roedel <jroedel@suse.de>, Borislav Petkov <bp@suse.de>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 344/575] x86/sev: Fix stack type check in vc_switch_off_ist()
Date:   Mon, 15 Nov 2021 18:01:09 +0100
Message-Id: <20211115165355.694642447@linuxfoundation.org>
In-Reply-To: <20211115165343.579890274@linuxfoundation.org>
References: <20211115165343.579890274@linuxfoundation.org>
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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 7692bf7908e6c..143fcb8af38f4 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -701,7 +701,7 @@ 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