From:   Nikita Zhandarovich <n.zhandarovich@fintech.ru>
To:     Dave Hansen <dave.hansen@linux.intel.com>
CC:     Nikita Zhandarovich <n.zhandarovich@fintech.ru>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        <linux-kernel@vger.kernel.org>, <lvc-project@linuxtesting.org>
Subject: [PATCH] x86/mm: Fix use of uninitialized buffer in sme_enable()
Date:   Thu, 2 Feb 2023 10:25:38 -0800
Message-ID: <20230202182538.29352-1-n.zhandarovich@fintech.ru>
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Precedence: bulk

cmdline_find_option() may fail before doing any initialization of
buffer array. This may lead to unpredictable results when the same
buffer is used later in calls to strncmp() function.
Fix the issue by initializing the buffer to an empty string.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 1cd9c22fee3a ("x86/mm/encrypt: Move page table helpers into separate translation unit")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
---
 arch/x86/mm/mem_encrypt_identity.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index 88cccd65029d..6b84243bfd54 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -509,7 +509,7 @@ void __init sme_enable(struct boot_params *bp)
 	unsigned long feature_mask;
 	bool active_by_default;
 	unsigned long me_mask;
-	char buffer[16];
+	char buffer[16] = "";
 	bool snp;
 	u64 msr;
 
-- 
2.25.1