fix SEGV touching uninitialized memory

shyouhei · shyouhei · commit bfe580681d7d · 2018-01-02T06:42:00.000Z
This function can be called from Init_VM(). No assumption can be made about object internals. (lldb) run Process 15734 launched: './miniruby' (x86_64) Process 15734 stopped * thread #1: tid = 0x1441d4, 0x00000001000bdfcb miniruby`rb_raw_iseq_info(buff="0x0000000100f61f48 [0 ] T_IMEMO iseq", buff_size=256, iseq=0x0000000100f61f48) + 27 at gc.c:9273, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x50) frame #0: 0x00000001000bdfcb miniruby`rb_raw_iseq_info(buff="0x0000000100f61f48 [0 ] T_IMEMO iseq", buff_size=256, iseq=0x0000000100f61f48) + 27 at gc.c:9273 9270 static void 9271 rb_raw_iseq_info(char *buff, const int buff_size, const rb_iseq_t *iseq) 9272 { -> 9273 if (iseq->body->location.label) { 9274 VALUE path = rb_iseq_path(iseq); 9275 snprintf(buff, buff_size, "%s %s@%s:%d", buff, 9276 RSTRING_PTR(iseq->body->location.label), (lldb) p *iseq (rb_iseq_t) $0 = { flags = 28698 reserved1 = 0 body = 0x0000000000000000 aux = { compile_data = 0x0000000000000000 loader = (obj = 0, index = 0) trace_events = 0 } } (lldb) bt * thread #1: tid = 0x1441d4, 0x00000001000bdfcb miniruby`rb_raw_iseq_info(buff="0x0000000100f61f48 [0 ] T_IMEMO iseq", buff_size=256, iseq=0x0000000100f61f48) + 27 at gc.c:9273, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x50) * frame #0: 0x00000001000bdfcb miniruby`rb_raw_iseq_info(buff="0x0000000100f61f48 [0 ] T_IMEMO iseq", buff_size=256, iseq=0x0000000100f61f48) + 27 at gc.c:9273 frame #1: 0x00000001000bde72 miniruby`rb_raw_obj_info(buff="0x0000000100f61f48 [0 ] T_IMEMO iseq", buff_size=256, obj=4311097160) + 2786 at gc.c:9396 frame #2: 0x00000001000b7c5f miniruby`obj_info(obj=4311097160) + 95 at gc.c:9428 frame #3: 0x00000001000c16a8 miniruby`newobj_init(klass=0, flags=28698, v1=0, v2=0, v3=0, wb_protected=1, objspace=0x00000001007ee280, obj=4311097160) + 424 at gc.c:1887 frame #4: 0x00000001000b44c9 miniruby`newobj_of(klass=0, flags=28698, v1=0, v2=0, v3=0, wb_protected=1) + 217 at gc.c:1970 frame #5: 0x00000001000b464b miniruby`rb_imemo_new(type=imemo_iseq, v1=0, v2=0, v3=0, v0=0) + 75 at gc.c:2017 frame #6: 0x00000001000fd914 miniruby`iseq_imemo_alloc + 36 at iseq.h:156 frame #7: 0x00000001000f6e1d miniruby`iseq_alloc + 13 at iseq.c:211 frame #8: 0x00000001000f6bf8 miniruby`rb_iseq_new_with_opt(node=0x0000000000000000, name=4311097200, path=4311097200, realpath=8, first_lineno=1, parent=0x0000000000000000, type=ISEQ_TYPE_TOP, option=0x0000000100335c30) + 56 at iseq.c:519 frame #9: 0x00000001000f6bb6 miniruby`rb_iseq_new(node=0x0000000000000000, name=4311097200, path=4311097200, realpath=8, parent=0x0000000000000000, type=ISEQ_TYPE_TOP) + 86 at iseq.c:480 frame #10: 0x0000000100284bb0 miniruby`Init_VM + 1040 at vm.c:3022 frame #11: 0x00000001000d4f7d miniruby`rb_call_inits + 189 at inits.c:55 frame #12: 0x000000010009fe06 miniruby`ruby_setup + 198 at eval.c:61 frame #13: 0x000000010009fe5d miniruby`ruby_init + 13 at eval.c:78 frame #14: 0x00000001000009ed miniruby`main(argc=2, argv=0x00007fff5fbfdbf0) + 93 at main.c:41 frame #15: 0x00007fff88eda5ad libdyld.dylib`start + 1 (lldb) git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61564 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
diff --git a/gc.c b/gc.c
@@ -9270,7 +9270,7 @@ method_type_name(rb_method_type_t type)
 static void
 rb_raw_iseq_info(char *buff, const int buff_size, const rb_iseq_t *iseq)
 {
-    if (iseq->body->location.label) {
+    if (iseq->body && iseq->body->location.label) {
 	VALUE path = rb_iseq_path(iseq);
 	snprintf(buff, buff_size, "%s %s@%s:%d", buff,
 		 RSTRING_PTR(iseq->body->location.label),

Original file line number	Diff line number	Diff line change
`@@ -9270,7 +9270,7 @@ method_type_name(rb_method_type_t type)`
`9270`	`9270`	`static void`
`9271`	`9271`	`rb_raw_iseq_info(char buff, const int buff_size, const rb_iseq_t iseq)`
`9272`	`9272`	`{`
`9273`		`- if (iseq->body->location.label) {`
	`9273`	`+ if (iseq->body && iseq->body->location.label) {`
`9274`	`9274`	`VALUE path = rb_iseq_path(iseq);`
`9275`	`9275`	`snprintf(buff, buff_size, "%s %s@%s:%d", buff,`
`9276`	`9276`	`RSTRING_PTR(iseq->body->location.label),`