(perl #132655) nul terminate result of unpack "u" of invalid data

In the given test case, Perl_atof2() would run off the end of the PV,
producing an error from ASAN.

1 files changed, 4 insertions, 1 deletions

diff --git a/pp_pack.c b/pp_pack.c
index 5e9cc64301..f8be9d48ae 100644
--- a/pp_pack.c
+++ b/pp_pack.c
@@ -1727,7 +1727,10 @@ S_unpack_rec(pTHX_ tempsym_t* symptr, const char *s, const char *strbeg, const c
 	    if (!checksum) {
                 const STRLEN l = (STRLEN) (strend - s) * 3 / 4;
 		sv = sv_2mortal(newSV(l));
-		if (l) SvPOK_on(sv);
+		if (l) {
+                    SvPOK_on(sv);
+                    *SvEND(sv) = '\0';
+                }
 	    }
 
             /* Note that all legal uuencoded strings are ASCII printables, so