Fix sv_vcatpvfn %s with precision on non-NUL-terminated strings

The precision parameter to %s can be used to print non-NUL-terminated
strings, so use my_strnlen() to limit the length checking to the
specified length.

1 files changed, 4 insertions, 1 deletions

diff --git a/sv.c b/sv.c
index 070a0c195e..ac1fb4d823 100644
--- a/sv.c
+++ b/sv.c
@@ -12376,7 +12376,10 @@ Perl_sv_vcatpvfn_flags(pTHX_ SV *const sv, const char *const pat, const STRLEN p
 	    if (args) {
 		eptr = va_arg(*args, char*);
 		if (eptr)
-		    elen = strlen(eptr);
+                    if (has_precis)
+                        elen = my_strnlen(eptr, precis);
+                    else
+                        elen = strlen(eptr);
 		else {
 		    eptr = (char *)nullstr;
 		    elen = sizeof nullstr - 1;