ITS#9446 - Correctly parse gecos field

servers/slapd/back-passwd/search.c

@@ -321,7 +321,7 @@ pw2entry( Backend *be, struct passwd *pw, Entry *e )
 
 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
 	/*
-	 * if gecos is present, add it as a cn. first process it
+	 * if gecos is present, add user's full name as a cn. first process it
 	 * according to standard BSD usage. If the processed cn has
 	 * a space, use the tail as the surname.
 	 */
@@ -332,22 +332,39 @@ pw2entry( Backend *be, struct passwd *pw, Entry *e )
 		ber_str2bv( pw->pw_gecos, 0, 0, &val );
 		attr_merge_normalize_one( e, ad_desc, &val, NULL );
 
-		s = ber_bvchr( &val, ',' );
-		if ( s ) *s = '\0';
+		s = strchr( val.bv_val, (unsigned char)',' );
+		if ( s ) {
+			*s = '\0';
+			val.bv_len = s - val.bv_val;
+		}
 
-		s = ber_bvchr( &val, '&' );
+		s = strchr( val.bv_val, (unsigned char)'&' );
 		if ( s ) {
-			if( val.bv_len + pwlen < sizeof(buf) ) {
-				int i = s - val.bv_val;
-				strncpy( buf, val.bv_val, i );
-				s = buf + i;
-				strcpy( s, pw->pw_name );
-				*s = TOUPPER((unsigned char)*s);
-				strcat( s, val.bv_val + i + 1 );
+			unsigned r = sizeof buf;
+			/* if name with expanded `&` fits in buf */
+			if ( val.bv_len + pwlen <= r ) {
+				char * d = buf;
+
+				for (;;) {
+					size_t const i = s - val.bv_val;
+					memcpy( d, val.bv_val, i );
+					d += i;
+					memcpy( d, pw->pw_name, pwlen );
+					*d = TOUPPER((unsigned char)*pw->pw_name);
+					d += pwlen;
+					r -= pwlen + i;
+					val.bv_len -= i + 1;
+					val.bv_val  = s + 1;
+
+					s = strchr( val.bv_val, (unsigned char)'&' );
+					if (!(s && ( val.bv_len + pwlen <= r )))
+						break;
+				}
+				strcpy( d, val.bv_val );
+				val.bv_len = d - buf + val.bv_len;
 				val.bv_val = buf;
-			}
-		}
-		val.bv_len = strlen( val.bv_val );
+			} // 1st fits
+		} // 1st &
 
 		if ( val.bv_len && strcasecmp( val.bv_val, pw->pw_name ) ) {
 			attr_merge_normalize_one( e, slap_schema.si_ad_cn, &val, NULL );