CRASH (ui_tests fixup_last_cti targeter==NULL)

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on October 12, 2011 15:21:53_

I believe this is while running this test but it's during full ui_tests
suite under plain DR and sometimes the suite keeps going, will try to repro later:

[ RUN ] BookmarksUITest.CommandAgainGoesBackToBookmarksTab

this is under --single-process with issue #577 fixed

```
0:000> .exr 1af13ba8
ExceptionAddress: 01990e78 (dynamorio!fixup_last_cti+0x00000288)
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000000
Parameter[1]: 0000003c
Attempt to read from address 0000003c

0:000> .cxr 1af13bf8
eax=1af21c98 ebx=00000000 ecx=00000008 edx=373e38e0 esi=1af21c98 edi=00000000
eip=01990e78 esp=1af13ee0 ebp=00000000 iopl=0 nv up ei pl zr na po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246
dynamorio!fixup_last_cti+0x288:
01990e78 8b773c mov esi,[edi+0x3c] ds:002b:0000003c=????????
0:000> kn
**\* Stack trace for last set context - .thread/.cxr resets it
# ChildEBP RetAddr
00 1af13f18 01993e90 dynamorio!fixup_last_cti+0x288 [e:\src\dr\git\src\core\x86\interp.c @ 5298]
01 1af13f54 01965c30 dynamorio!extend_trace+0x60 [e:\src\dr\git\src\core\x86\interp.c @ 5655]
02 1af13f74 019660b5 dynamorio!internal_extend_trace+0xf0 [e:\src\dr\git\src\core\monitor.c @ 1746]
03 1af13fb4 0195a462 dynamorio!monitor_cache_enter+0x345 [e:\src\dr\git\src\core\monitor.c @ 2164]
04 1ae94800 0106e2d5 dynamorio!dispatch+0x182 [e:\src\dr\git\src\core\dispatch.c @ 169]

instr_t *next = targeter->next;
```

so failed to find targeter

_Original issue: http://code.google.com/p/dynamorio/issues/detail?id=582_

Start with the reported BookmarksUITest.CommandAgainGoesBackToBookmarksTab case in the full ui_tests suite under plain DR and --single-process. Read fixup_last_cti in src/core/x86/interp.c around line 5298, then follow extend_trace in interp.c and monitor_cache_enter in src/core/monitor.c. Done means reproducing and resolving the targeter==NULL access violation without regressing the suite.

Written by the indexing model from the issue text.