[PATCH 03/28] ARM: atags: Replace strlcat() with snprintf() for cmdline extend

[Bill Wendling]

When CONFIG_CMDLINE_EXTEND is enabled, parse_tag_cmdline() uses two
strlcat() calls to append a space and the bootloader tag command line to
default_command_line.

In preparation for removing the deprecated strlcat() API[1], compute the
length of default_command_line once and append the space and tag command
line in a single snprintf() call.

Link: https://github.com/KSPP/linux/issues/370 [1]
Cc: codemender-patching+linux@xxxxxxxxxx
Assisted-by: developer:gpt-4o [editor_update_file, shell_command_run]
Signed-off-by: Bill Wendling <morbo@xxxxxxxxxx>
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---
 arch/arm/kernel/atags_parse.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kernel/atags_parse.c b/arch/arm/kernel/atags_parse.c
index 4ec591bde3df..21140b44d96e 100644
--- a/arch/arm/kernel/atags_parse.c
+++ b/arch/arm/kernel/atags_parse.c
@@ -121,9 +121,10 @@ __tagtable(ATAG_REVISION, parse_tag_revision);
 static int __init parse_tag_cmdline(const struct tag *tag)
 {
 #if defined(CONFIG_CMDLINE_EXTEND)
-	strlcat(default_command_line, " ", COMMAND_LINE_SIZE);
-	strlcat(default_command_line, tag->u.cmdline.cmdline,
-		COMMAND_LINE_SIZE);
+	size_t len = strlen(default_command_line);
+
+	snprintf(default_command_line + len, COMMAND_LINE_SIZE - len,
+		 " %s", tag->u.cmdline.cmdline);
 #elif defined(CONFIG_CMDLINE_FORCE)
 	pr_warn("Ignoring tag cmdline (using the default kernel command line)\n");
 #else
-- 
2.55.0.1032.g73a4cd73de-goog