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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Andy Lutomirski <luto@amacapital.net>,
        Marco Elver <elver@google.com>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 033/109] x86/entry: Increase entry_stack size to a full page
Date:   Tue, 14 Jul 2020 20:43:36 +0200
Message-Id: <20200714184107.106217550@linuxfoundation.org>
In-Reply-To: <20200714184105.507384017@linuxfoundation.org>
References: <20200714184105.507384017@linuxfoundation.org>
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From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit c7aadc09321d8f9a1d3bd1e6d8a47222ecddf6c5 ]

Marco crashed in bad_iret with a Clang11/KCSAN build due to
overflowing the stack. Now that we run C code on it, expand it to a
full page.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Reported-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Tested-by: Marco Elver <elver@google.com>
Link: https://lkml.kernel.org/r/20200618144801.819246178@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/include/asm/processor.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 54f5d54280f60..a07dfdf7759ec 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -334,7 +334,7 @@ struct x86_hw_tss {
 #define INVALID_IO_BITMAP_OFFSET	0x8000
 
 struct entry_stack {
-	unsigned long		words[64];
+	char	stack[PAGE_SIZE];
 };
 
 struct entry_stack_page {
-- 
2.25.1