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From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Masami Hiramatsu <mhiramat@kernel.org>,
        Padmanabha Srinivasaiah <treasure4paddy@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        Randy Dunlap <rdunlap@infradead.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Sami Tolvanen <samitolvanen@google.com>,
        Nathan Chancellor <nathan@kernel.org>, llvm@lists.linux.dev,
        Masahiro Yamada <masahiroy@kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
Subject: [PATCH v8 2/4] bootconfig: Check the checksum before removing the bootconfig from initrd
Date:   Wed,  6 Apr 2022 11:31:09 +0900
Message-Id: <164921226891.1090670.16955839243639298134.stgit@devnote2>
In-Reply-To: <164921224829.1090670.9700650651725930602.stgit@devnote2>
References: <164921224829.1090670.9700650651725930602.stgit@devnote2>
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Check the bootconfig's checksum before removing the bootcinfig data
from initrd to avoid modifying initrd by mistake.
This will also simplifies the get_boot_config_from_initrd() interface.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 init/main.c |   22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/init/main.c b/init/main.c
index 560f45c27ffe..4f3ba3b84e34 100644
--- a/init/main.c
+++ b/init/main.c
@@ -265,7 +265,7 @@ static int __init loglevel(char *str)
 early_param("loglevel", loglevel);
 
 #ifdef CONFIG_BLK_DEV_INITRD
-static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
+static void * __init get_boot_config_from_initrd(u32 *_size)
 {
 	u32 size, csum;
 	char *data;
@@ -299,17 +299,20 @@ static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
 		return NULL;
 	}
 
+	if (xbc_calc_checksum(data, size) != csum) {
+		pr_err("bootconfig checksum failed\n");
+		return NULL;
+	}
+
 	/* Remove bootconfig from initramfs/initrd */
 	initrd_end = (unsigned long)data;
 	if (_size)
 		*_size = size;
-	if (_csum)
-		*_csum = csum;
 
 	return data;
 }
 #else
-static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
+static void * __init get_boot_config_from_initrd(u32 *_size)
 {
 	return NULL;
 }
@@ -408,12 +411,12 @@ static void __init setup_boot_config(void)
 	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
 	const char *msg;
 	int pos;
-	u32 size, csum;
+	u32 size;
 	char *data, *err;
 	int ret;
 
 	/* Cut out the bootconfig data even if we have no bootconfig option */
-	data = get_boot_config_from_initrd(&size, &csum);
+	data = get_boot_config_from_initrd(&size);
 
 	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 	err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
@@ -437,11 +440,6 @@ static void __init setup_boot_config(void)
 		return;
 	}
 
-	if (xbc_calc_checksum(data, size) != csum) {
-		pr_err("bootconfig checksum failed\n");
-		return;
-	}
-
 	ret = xbc_init(data, size, &msg, &pos);
 	if (ret < 0) {
 		if (pos < 0)
@@ -470,7 +468,7 @@ static void __init exit_boot_config(void)
 static void __init setup_boot_config(void)
 {
 	/* Remove bootconfig data from initrd */
-	get_boot_config_from_initrd(NULL, NULL);
+	get_boot_config_from_initrd(NULL);
 }
 
 static int __init warn_bootconfig(char *str)