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From:   Ard Biesheuvel <ardb@kernel.org>
To:     linux-efi@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>
Cc:     Ard Biesheuvel <ardb@kernel.org>, linux-kernel@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>,
        Arvind Sankar <nivedita@alum.mit.edu>,
        Borislav Petkov <bp@suse.de>,
        Colin Ian King <colin.king@canonical.com>,
        Gary Lin <glin@suse.com>, Jiri Slaby <jslaby@suse.cz>,
        Sergey Shatunov <me@prok.pw>, Takashi Iwai <tiwai@suse.de>
Subject: [PATCH 1/9] efi/cper: Use scnprintf() for avoiding potential buffer overflow
Date:   Thu,  9 Apr 2020 15:04:26 +0200
Message-Id: <20200409130434.6736-2-ardb@kernel.org>
In-Reply-To: <20200409130434.6736-1-ardb@kernel.org>
References: <20200409130434.6736-1-ardb@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Takashi Iwai <tiwai@suse.de>

Since snprintf() returns the would-be-output size instead of the
actual output size, the succeeding calls may go beyond the given
buffer limit.  Fix it by replacing with scnprintf().

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20200311072145.5001-1-tiwai@suse.de
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/firmware/efi/cper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/cper.c b/drivers/firmware/efi/cper.c
index b1af0de2e100..9d2512913d25 100644
--- a/drivers/firmware/efi/cper.c
+++ b/drivers/firmware/efi/cper.c
@@ -101,7 +101,7 @@ void cper_print_bits(const char *pfx, unsigned int bits,
 		if (!len)
 			len = snprintf(buf, sizeof(buf), "%s%s", pfx, str);
 		else
-			len += snprintf(buf+len, sizeof(buf)-len, ", %s", str);
+			len += scnprintf(buf+len, sizeof(buf)-len, ", %s", str);
 	}
 	if (len)
 		printk("%s\n", buf);
-- 
2.17.1