# Uninitialized \_tag.retval value is used

**URL:** <https://www.ruby-forum.com/t/uninitialized-tag-retval-value-is-used/136489>\
**Category:** Development\
**Created:** [May 2, 2008, 5:16pm UTC](https://www.ruby-forum.com/t/uninitialized-tag-retval-value-is-used/136489 "2008-05-02T17:16:04Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Tanaka\_A](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/c67d28/32.png) [@Tanaka\_A](https://www.ruby-forum.com/u/Tanaka_A)\
**Post date:** [May 2, 2008, 5:16pm UTC](https://www.ruby-forum.com/t/uninitialized-tag-retval-value-is-used/136489/1 "2008-05-02T17:16:04Z")

</div>

e$B5$$,$D$$$?$N$G$9$,!"e(B\_tag.retval e$B$r=i4|2=$7$J$$$G;H$&$3$H$,$"e(B  
e$B$k$h$&$G$9!#e(B

e$B0J2\<$N$h$&$Ke(B TH\_PUSH\_TAG(th); e$B$ND\>8e$G!"$^$@e(B \_tag  
e$B$,=i4|2=$5e(B  
e$B$l$F$_$i$:!"$I$s$JCM$G$b$_$+$7$/$J$$\>uBV$G!"e(B123456 e$B$H$$$&CMe(B  
e$B$rBeF~$7$^$9!#e(B

e$B$=$7$F!"e(Bvm\_make\_jump\_tag\_but\_local\_jump e$B$Ge(B retval  
e$B$r;H$&$H$-e(B  
e$B$Ke(B 123456 e$B$H$$$&$K$J$k$I$&$+$rD4$Y$k$h$&$K$7$^$9!#e(B

# Index: vm.c

— vm.c (revision 16271)  
+++ vm.c (working copy)  
@@ -912,7 +912,11 @@ vm\_make\_jump\_tag\_but\_local\_jump(int stat  
VALUE result = Qnil;

```
 if (val == Qundef)

```

- {  
val = GET\_THREAD()-\>tag-\>retval;

- 

```
   if(val == 123456)

```

- 

```
       fprintf(stderr, "retval is 123456\n");

```

- }  
switch (state) {  
case 0:  
break;  
@@ -1142,6 +1146,7 @@ vm\_eval\_body(rb\_thread\_t \*th)  
VALUE initial = 0;

- \_tag.retval = 123456;  
if ((state = EXEC\_TAG()) == 0) {  
vm\_loop\_start:  
result = vm\_eval(th, initial);

e$B$=$7$F!"0J2\<$Ne(B s1.rb, s2.rb, s3.rb e$B$rMQ0U$7$^$9!#e(B

% cat s1.rb  
def m  
proc {  
load “s2.rb”  
}.call  
ensure  
GC.start  
end  
m

% cat s2.rb  
require ‘s3.rb’  
X.call

% cat s3.rb  
X = proc do  
lambda {  
return  
}.call  
end

e$B$=$7$F!"\>e5-$NJQ99$r9T$C$?e(B ruby e$B$Ge(B s1.rb  
e$B$r\<B9T$9$k$H!“e(B  
retval e$B$,e(B 123456 e$B$K$J$k$3$H$,8!=P$5$l!”$=$N8e$Ge(B SEGV  
e$B$7$^$9!#e(B

% ./ruby s1.rb  
retval is 123456  
s1.rb:6: [BUG] Segmentation fault  
ruby 1.9.0 (2008-05-02 revision 16271) [i686-linux]

## – control frame ---------- c:0006 p:---- s:0015 b:0015 l:000014 d:000014 CFUNC :start c:0005 p:0013 s:0012 b:0012 l:0008bc d:000011 BLOCK s1.rb:6 c:0004 p:0027 s:0010 b:0009 l:0008bc d:0008bc METHOD s1.rb:6 c:0003 p:0012 s:0006 b:0006 l:000005 d:000005 TOP s1.rb:8 c:0002 p:---- s:0004 b:0004 l:000003 d:000003 FINISH :private\_class\_method c:0001 p:0000 s:0002 b:0002 l:000001 d:000001 TOP :17

## DBG\> : “s1.rb:6:in `ensure in m'" DBG> : "s1.rb:6:in`m’” DBG\> : “s1.rb:8:in `’” – backtrace of native function call (Use addr2line) – 0x8100595 0x8126ade 0x8126b3b 0x80cd770 0xb7fea440 0x8064f01 0x80f5d9d 0x8064aab 0x80f5c91 0x80d2200 0x80f6080 0x8064aab 0x8065425 0x8065d60 0x8065d7b 0x80fed93 0x80fa715 0x80fdf84 0x80fe2bd 0x805afbf 0x805e67e 0x8058ab5 0xb7e4bea8 0x80589b1

zsh: abort (core dumped) ./ruby s1.rb  
% gdb ruby core.3723  
GNU gdb 6.4.90-debian  
Copyright © 2006 Free Software Foundation, Inc.  
GDB is free software, covered by the GNU General Public  
License, and you are  
welcome to change it and/or distribute copies of it under  
certain conditions.  
Type “show copying” to see the conditions.  
There is absolutely no warranty for GDB. Type “show  
warranty” for details.  
This GDB was configured as “i486-linux-gnu”…Using host  
libthread\_db library “/lib/tls/i686/cmov/libthread\_db.so.1”.

warning: Can’t read pathname for load map: Input/output  
error.  
Reading symbols from  
/lib/tls/i686/cmov/libpthread.so.0…done.  
Loaded symbols for /lib/tls/i686/cmov/libpthread.so.0  
Reading symbols from /lib/tls/i686/cmov/librt.so.1…done.  
Loaded symbols for /lib/tls/i686/cmov/librt.so.1  
Reading symbols from /lib/tls/i686/cmov/libdl.so.2…done.  
Loaded symbols for /lib/tls/i686/cmov/libdl.so.2  
Reading symbols from  
/lib/tls/i686/cmov/libcrypt.so.1…done.  
Loaded symbols for /lib/tls/i686/cmov/libcrypt.so.1  
Reading symbols from /lib/tls/i686/cmov/libm.so.6…done.  
Loaded symbols for /lib/tls/i686/cmov/libm.so.6  
Reading symbols from /lib/tls/i686/cmov/libc.so.6…done.  
Loaded symbols for /lib/tls/i686/cmov/libc.so.6  
Reading symbols from /lib/ld-linux.so.2…Reading symbols  
from /usr/lib/debug/lib/ld-2.3.6.so…done.  
done.  
Loaded symbols for /lib/ld-linux.so.2  
Reading symbols from  
/tmp/b/lib/ruby/1.9.0/i686-linux/enc/encdb.so…done.  
Loaded symbols for  
/tmp/b/lib/ruby/1.9.0/i686-linux/enc/encdb.so  
Reading symbols from  
/tmp/b/lib/ruby/1.9.0/i686-linux/enc/trans/transdb.so…done.  
Loaded symbols for  
/tmp/b/lib/ruby/1.9.0/i686-linux/enc/trans/transdb.so  
Reading symbols from /lib/libgcc\_s.so.1…done.  
Loaded symbols for /lib/libgcc\_s.so.1  
Core was generated by `./ruby s1.rb’.  
Program terminated with signal 6, Aborted.  
#0 0xb7fea410 in ?? ()  
(gdb) bt  
#0 0xb7fea410 in ?? ()  
#1 0xbfffdb9c in ?? ()  
#2 0x00000006 in ?? ()  
#3 0x00000e8b in ?? ()  
#4 0xb7e5f811 in raise () from /lib/tls/i686/cmov/libc.so.6  
#5 0xb7e60fb9 in abort () from /lib/tls/i686/cmov/libc.so.6  
#6 0x08126b40 in rb\_bug (fmt=0x815404d “Segmentation  
fault”) at error.c:226  
#7 0x080cd770 in sigsegv (sig=11) at signal.c:551  
#8 0xb7fea440 in ?? ()  
#9 0x0000000b in ?? ()  
#10 0xbfffdd2c in ?? ()  
#11 0xbfffddac in ?? ()  
#12 0x0000000b in ?? ()  
#13 0x00000000 in ?? ()  
(gdb)