shared/runtime/pyexec: Fix UBSan error in pyexec_stdin().

pi-anl · pi-anl · commit d486bb72d0f1 · 2025-08-19T11:11:27.000+10:00
Use mp_lexer_new_from_fd() instead of mp_reader_new_file_from_fd() to
match the original execute_from_lexer() behavior. This avoids undefined
behavior detected by UBSan where bool close_fd contained non-bool values.

Signed-off-by: Andrew Leech &lt;andrew.leech@planetinnovation.com.au&gt;
diff --git a/shared/runtime/pyexec.c b/shared/runtime/pyexec.c
@@ -766,10 +766,8 @@ int pyexec_str_single(const char *str, bool allow_keyboard_interrupt) {
 }
 
 int pyexec_stdin(void) {
-    mp_reader_t reader;
-    mp_reader_new_file_from_fd(&reader, 0, false);
-    mp_uint_t exec_flags = EXEC_FLAG_SOURCE_IS_READER;
-    return parse_compile_execute(&reader, MP_PARSE_FILE_INPUT, exec_flags, NULL);
+    mp_lexer_t *lex = mp_lexer_new_from_fd(MP_QSTR__lt_stdin_gt_, 0, false);
+    return parse_compile_execute(lex, MP_PARSE_FILE_INPUT, 0, NULL);
 }
 #endif
 

Original file line number	Diff line number	Diff line change
`@@ -766,10 +766,8 @@ int pyexec_str_single(const char *str, bool allow_keyboard_interrupt) {`
`766`	`766`	`}`
`767`	`767`
`768`	`768`	`int pyexec_stdin(void) {`
`769`		`- mp_reader_t reader;`
`770`		`- mp_reader_new_file_from_fd(&reader, 0, false);`
`771`		`- mp_uint_t exec_flags = EXEC_FLAG_SOURCE_IS_READER;`
`772`		`- return parse_compile_execute(&reader, MP_PARSE_FILE_INPUT, exec_flags, NULL);`
	`769`	`+ mp_lexer_t *lex = mp_lexer_new_from_fd(MP_QSTR__lt_stdin_gt_, 0, false);`
	`770`	`+ return parse_compile_execute(lex, MP_PARSE_FILE_INPUT, 0, NULL);`
`773`	`771`	`}`
`774`	`772`	`#endif`
`775`	`773`