[PATCH v2 4/4] kdb: Replace deprecated strcpy() with helper function in kdb_defcmd()

[Thorsten Blum <thorsten.blum@linux.dev>]

strcpy() is deprecated; use the new helper function kdb_strdup_dequote()
instead. In addition to string duplication similar to kdb_strdup(), it
also trims surrounding quotes from the input string if present.

kdb_strdup_dequote() also checks for a trailing quote in the input
string which was previously not checked.

Link: https://github.com/KSPP/linux/issues/88
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
Changes in v2:
- Copy 'len - 1' bytes using memcpy() as suggested by Doug
- Link to v1: https://lore.kernel.org/lkml/20250818181153.661431-4-thorsten.blum@linux.dev/
---
 kernel/debug/kdb/kdb_main.c    | 12 ++----------
 kernel/debug/kdb/kdb_private.h |  1 +
 kernel/debug/kdb/kdb_support.c | 29 +++++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index cdf91976eb7c..dddf2b5aad57 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -721,20 +721,12 @@ static int kdb_defcmd(int argc, const char **argv)
 	mp->name = kdb_strdup(argv[1], GFP_KDB);
 	if (!mp->name)
 		goto fail_name;
-	mp->usage = kdb_strdup(argv[2], GFP_KDB);
+	mp->usage = kdb_strdup_dequote(argv[2], GFP_KDB);
 	if (!mp->usage)
 		goto fail_usage;
-	mp->help = kdb_strdup(argv[3], GFP_KDB);
+	mp->help = kdb_strdup_dequote(argv[3], GFP_KDB);
 	if (!mp->help)
 		goto fail_help;
-	if (mp->usage[0] == '"') {
-		strcpy(mp->usage, argv[2]+1);
-		mp->usage[strlen(mp->usage)-1] = '\0';
-	}
-	if (mp->help[0] == '"') {
-		strcpy(mp->help, argv[3]+1);
-		mp->help[strlen(mp->help)-1] = '\0';
-	}
 
 	INIT_LIST_HEAD(&kdb_macro->statements);
 	defcmd_in_progress = true;
diff --git a/kernel/debug/kdb/kdb_private.h b/kernel/debug/kdb/kdb_private.h
index d2520d72b1f5..a2fc7d2bc9fc 100644
--- a/kernel/debug/kdb/kdb_private.h
+++ b/kernel/debug/kdb/kdb_private.h
@@ -110,6 +110,7 @@ extern int kdbgetaddrarg(int, const char **, int*, unsigned long *,
 extern int kdbgetsymval(const char *, kdb_symtab_t *);
 extern int kdbnearsym(unsigned long, kdb_symtab_t *);
 extern char *kdb_strdup(const char *str, gfp_t type);
+extern char *kdb_strdup_dequote(const char *str, gfp_t type);
 extern void kdb_symbol_print(unsigned long, const kdb_symtab_t *, unsigned int);
 
 /* Routine for debugging the debugger state. */
diff --git a/kernel/debug/kdb/kdb_support.c b/kernel/debug/kdb/kdb_support.c
index d36281142fa1..56f7b906e7cc 100644
--- a/kernel/debug/kdb/kdb_support.c
+++ b/kernel/debug/kdb/kdb_support.c
@@ -255,6 +255,35 @@ char *kdb_strdup(const char *str, gfp_t type)
 	return s;
 }
 
+/*
+ * kdb_strdup_dequote - same as kdb_strdup(), but trims surrounding quotes from
+ *			the input string if present.
+ * Remarks:
+ *	Quotes are only removed if there is both a leading and a trailing quote.
+ */
+char *kdb_strdup_dequote(const char *str, gfp_t type)
+{
+	size_t len = strlen(str);
+	char *s;
+
+	if (str[0] == '"' && len > 1 && str[len - 1] == '"') {
+		/* trim both leading and trailing quotes */
+		str++;
+		len -= 2;
+	}
+
+	len++; /* add space for NUL terminator */
+
+	s = kmalloc(len, type);
+	if (!s)
+		return NULL;
+
+	memcpy(s, str, len - 1);
+	s[len - 1] = '\0';
+
+	return s;
+}
+
 /*
  * kdb_getarea_size - Read an area of data.  The kdb equivalent of
  *	copy_from_user, with kdb messages for invalid addresses.
-- 
2.50.1