[PATCH 5.15.y 3/4] tools/bootconfig: Cleanup bootconfig footer size calculations

[Sasha Levin <sashal@kernel.org>]

From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>

[ Upstream commit 26dda57695090e05c1a99c3e8f802f862d1ac474 ]

There are many same pattern of 8 + BOOTCONFIG_MAGIC_LEN for calculating
the size of bootconfig footer. Use BOOTCONFIG_FOOTER_SIZE macro to
clean up those magic numbers.

Link: https://lore.kernel.org/all/175211425693.2591046.16029516706923643510.stgit@mhiramat.tok.corp.google.com/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Stable-dep-of: 462d0b066b61 ("tools/bootconfig: Fix integer overflow and truncation in size checks")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/bootconfig/main.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index ba0be1679df3e..31536110699ec 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -17,6 +17,10 @@
 
 #define pr_err(fmt, ...) fprintf(stderr, fmt, ##__VA_ARGS__)
 
+/* Bootconfig footer is [size][csum][BOOTCONFIG_MAGIC]. */
+#define BOOTCONFIG_FOOTER_SIZE	\
+	(sizeof(uint32_t) * 2 + BOOTCONFIG_MAGIC_LEN)
+
 static int xbc_show_value(struct xbc_node *node, bool semicolon)
 {
 	const char *val, *eol;
@@ -189,7 +193,7 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	if (ret < 0)
 		return -errno;
 
-	if (stat.st_size < 8 + BOOTCONFIG_MAGIC_LEN)
+	if (stat.st_size < BOOTCONFIG_FOOTER_SIZE)
 		return 0;
 
 	if (lseek(fd, -BOOTCONFIG_MAGIC_LEN, SEEK_END) < 0)
@@ -202,7 +206,7 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	if (memcmp(magic, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN) != 0)
 		return 0;
 
-	if (lseek(fd, -(8 + BOOTCONFIG_MAGIC_LEN), SEEK_END) < 0)
+	if (lseek(fd, -BOOTCONFIG_FOOTER_SIZE, SEEK_END) < 0)
 		return pr_errno("Failed to lseek for size", -errno);
 
 	if (read(fd, &size, sizeof(uint32_t)) < 0)
@@ -214,12 +218,12 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	csum = le32toh(csum);
 
 	/* Wrong size error  */
-	if (stat.st_size < size + 8 + BOOTCONFIG_MAGIC_LEN) {
+	if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) {
 		pr_err("bootconfig size is too big\n");
 		return -E2BIG;
 	}
 
-	if (lseek(fd, stat.st_size - (size + 8 + BOOTCONFIG_MAGIC_LEN),
+	if (lseek(fd, stat.st_size - (size + BOOTCONFIG_FOOTER_SIZE),
 		  SEEK_SET) < 0)
 		return pr_errno("Failed to lseek", -errno);
 
@@ -350,7 +354,7 @@ static int delete_xbc(const char *path)
 		ret = fstat(fd, &stat);
 		if (!ret)
 			ret = ftruncate(fd, stat.st_size
-					- size - 8 - BOOTCONFIG_MAGIC_LEN);
+					- size - BOOTCONFIG_FOOTER_SIZE);
 		if (ret)
 			ret = -errno;
 	} /* Ignore if there is no boot config in initrd */
@@ -380,8 +384,7 @@ static int apply_xbc(const char *path, const char *xbc_path)
 	csum = xbc_calc_checksum(buf, size);
 
 	/* Backup the bootconfig data */
-	data = calloc(size + BOOTCONFIG_ALIGN +
-		      sizeof(uint32_t) + sizeof(uint32_t) + BOOTCONFIG_MAGIC_LEN, 1);
+	data = calloc(size + BOOTCONFIG_ALIGN + BOOTCONFIG_FOOTER_SIZE, 1);
 	if (!data)
 		return -ENOMEM;
 	memcpy(data, buf, size);
@@ -428,7 +431,7 @@ static int apply_xbc(const char *path, const char *xbc_path)
 	}
 
 	/* To align up the total size to BOOTCONFIG_ALIGN, get padding size */
-	total_size = stat.st_size + size + sizeof(uint32_t) * 2 + BOOTCONFIG_MAGIC_LEN;
+	total_size = stat.st_size + size + BOOTCONFIG_FOOTER_SIZE;
 	pad = ((total_size + BOOTCONFIG_ALIGN - 1) & (~BOOTCONFIG_ALIGN_MASK)) - total_size;
 	size += pad;
 
-- 
2.53.0