[glibc/azanella/ubsan-undef] locate: Fix UB on memcpy call

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a6d7220313faa8857d82d5fd6bf8485383048e2b

commit a6d7220313faa8857d82d5fd6bf8485383048e2b
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Thu Apr 17 18:03:16 2025 -0300

    locate: Fix UB on memcpy call
    
    The ubsan triggers:
    
    UBSAN: Undefined behaviour in programs/charmap.c:908:2 null pointer passed as argument 2, nonnull attribute declared at unknown:0:0
    
    This is not an isseu since size is always '0' in this case.

Diff:
---
 locale/programs/charmap.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/locale/programs/charmap.c b/locale/programs/charmap.c
index 7768a7a7fc..1867c3735b 100644
--- a/locale/programs/charmap.c
+++ b/locale/programs/charmap.c
@@ -904,9 +904,9 @@ number of bytes for byte sequence of beginning and end of range not the same: %d
 	(struct width_rule *) obstack_alloc (&result->mem_pool,
 					     (new_size
 					      * sizeof (struct width_rule)));
-
-      memcpy (new_rules, result->width_rules,
-	      result->nwidth_rules_max * sizeof (struct width_rule));
+      if (result->width_rules != NULL)
+	memcpy (new_rules, result->width_rules,
+		result->nwidth_rules_max * sizeof (struct width_rule));
 
       result->width_rules = new_rules;
       result->nwidth_rules_max = new_size;