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CRASH on detach at -loglevel 4 in dump_unmasked #5618

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derekbruening opened this issue Aug 17, 2022 · 0 comments · Fixed by #5619
Closed

CRASH on detach at -loglevel 4 in dump_unmasked #5618

derekbruening opened this issue Aug 17, 2022 · 0 comments · Fixed by #5619

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@derekbruening
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I hit this crash while running the tool.drcacheoff.gencode test for #2062.
The info->sighand has been freed and set to NULL, but afterward some diagnostic code tries to read it.

<Detaching from application /dr/git/build_x64_dbg_tests/suite/tests/bin/tool.drcacheoff.gencode (1413152)>
<Detaching from process, entering final cleanup>
drmemtrace exiting process 1413152; traced 16429 references in 5 writeouts.
flush_instr_encodings: Wrote 92/92 bytes to encoding file
Wrote 92 bytes to encoding file

Program received signal SIGSEGV, Segmentation fault.
0x00005555558879fb in dump_unmasked (dcontext=0x7ffdf7a70080, where=0x555555a13cd0 <__FUNCTION__.24> "signal_swap_mask")
    at /dr/git/src/core/unix/signal.c:338
338             LOG(THREAD, LOG_ASYNCH, 3, "[%d]=%d ", i, info->sighand->threads_unmasked[i]);
(gdb) bt
#0  0x00005555558879fb in dump_unmasked (dcontext=0x7ffdf7a70080, where=0x555555a13cd0 <__FUNCTION__.24> "signal_swap_mask")
    at /dr/git/src/core/unix/signal.c:338
#1  0x000055555588dec0 in signal_swap_mask (dcontext=0x7ffdf7a70080, to_app=true) at /dr/git/src/core/unix/signal.c:2415
#2  0x000055555588b038 in signal_thread_exit (dcontext=0x7ffdf7a70080, other_thread=false) at /dr/git/src/core/unix/signal.c:1548
#3  0x00005555558708be in os_thread_exit (dcontext=0x7ffdf7a70080, other_thread=false) at /dr/git/src/core/unix/os.c:2495
#4  0x00005555555f495c in dynamo_thread_exit_common (dcontext=0x7ffdf7a70080, id=1413152, other_thread=false)
    at /dr/git/src/core/dynamo.c:2621
#5  0x00005555555f4b40 in dynamo_thread_exit () at /dr/git/src/core/dynamo.c:2693
#6  0x00005555555f24b0 in dynamo_shared_exit (toexit=0x7ffdf7a1bda0) at /dr/git/src/core/dynamo.c:1116
#7  0x00005555557820ad in detach_on_permanent_stack (internal=true, do_cleanup=true, drstats=0x0) at /dr/git/src/core/synch.c:2267
#8  0x00005555555f54ef in dr_app_stop_and_cleanup_with_stats (drstats=0x0) at /dr/git/src/core/dynamo.c:2833
#9  0x00005555555f54a0 in dr_app_stop_and_cleanup () at /dr/git/src/core/dynamo.c:2816
#10 0x00005555555dda46 in gather_trace () at /dr/git/src/clients/drcachesim/tests/burst_gencode.cpp:206
#11 0x00005555555dddf9 in main (argc=1, argv=0x7fffffffd998) at /dr/git/src/clients/drcachesim/tests/burst_gencode.cpp:250
(gdb) p info
$1 = (thread_sig_info_t *) 0x7ffdf7a89148
(gdb) p info->sighand
$2 = (sighand_info_t *) 0x0
(gdb) q
derekbruening added a commit that referenced this issue Aug 18, 2022
@derekbruening
i#2062 memtrace nonmod: Raw2trace parsing of encoding file
a2fbfe4 
Adds raw2trace parsing of the encoding file used by the tracer to
store instruction encodings for generated code.  This involves the
following changes:

+ Adds encoding file parsing to module_mapper_t.
+ Changes module map queries to use new module_mapper_t interfaces instead,
  which handle generated code.
+ Changes block lookup to use the modidx,modoffs pair as the key rather than
  the absolute pc.

The changes are compatibility-breaking for raw2trace_t which now takes
an encoding file parameter in the middle of existing parameters.
Updates existing uses.

For module_mapper_t the encoding file is added last with a default
value to preserve compatibility for existing analysis tools like
opcode_mix and view.  It is assumed that encodings for generated code
will be added to the final trace file and thus these tools will not
need a module_mapper_t interface for generated code.

Augments the tool.drcacheoff.gencode test to post-process the trace
and ensure the generated code PC is observed.

Fixes a -loglevel 4 signal dump_unmaksed() crash on detach i#5618 hit
in the gencode test; confirmed the test is crash-free at loglevel 4
with the fix.

Issue: #2062
Fixes #5618
@derekbruening derekbruening mentioned this issue Aug 18, 2022
Merged
derekbruening added a commit that referenced this issue Aug 19, 2022
@derekbruening
i#2062 memtrace nonmod part 2: Raw2trace parsing of encoding file (#5619
91c304a 
)

Adds raw2trace parsing of the encoding file used by the tracer to
store instruction encodings for generated code.  This involves the
following changes:

+ Adds encoding file parsing to module_mapper_t.
+ Changes module map queries to use new module_mapper_t interfaces instead,
  which handle generated code.
+ Changes block lookup to use the modidx,modoffs pair as the key rather than
  the absolute pc.  This runs into problems on 32-bit where the hashtable_t key
  is limited to pointer-sized.  To solve this, on 32-bit we use unordered_map, via
  a wrapper class block_hashtable_t to abstract away the differences.

The changes are compatibility-breaking for raw2trace_t which now takes
an encoding file parameter in the middle of existing parameters.
Updates existing uses.

For module_mapper_t the encoding file is added last with a default
value to preserve compatibility for existing analysis tools like
opcode_mix and view.  It is assumed that encodings for generated code
will be added to the final trace file and thus these tools will not
need a module_mapper_t interface for generated code.

Augments the tool.drcacheoff.gencode test to post-process the trace
and ensure the generated code PC is observed.

Fixes a -loglevel 4 signal dump_unmaksed() crash on detach i#5618 hit
in the gencode test; confirmed the test is crash-free at loglevel 4
with the fix.

Issue: #2062
Fixes #5618
derekbruening added a commit that referenced this issue Aug 26, 2022
@derekbruening
i#2062 memtrace nonmod part 2: Raw2trace parsing of encoding file (#5619
7daec6a 
)

Adds raw2trace parsing of the encoding file used by the tracer to
store instruction encodings for generated code.  This involves the
following changes:

+ Adds encoding file parsing to module_mapper_t.
+ Changes module map queries to use new module_mapper_t interfaces instead,
  which handle generated code.
+ Changes block lookup to use the modidx,modoffs pair as the key rather than
  the absolute pc.  This runs into problems on 32-bit where the hashtable_t key
  is limited to pointer-sized.  To solve this, on 32-bit we use unordered_map, via
  a wrapper class block_hashtable_t to abstract away the differences.

The changes are compatibility-breaking for raw2trace_t which now takes
an encoding file parameter in the middle of existing parameters.
Updates existing uses.

For module_mapper_t the encoding file is added last with a default
value to preserve compatibility for existing analysis tools like
opcode_mix and view.  It is assumed that encodings for generated code
will be added to the final trace file and thus these tools will not
need a module_mapper_t interface for generated code.

Augments the tool.drcacheoff.gencode test to post-process the trace
and ensure the generated code PC is observed.

Fixes a -loglevel 4 signal dump_unmaksed() crash on detach i#5618 hit
in the gencode test; confirmed the test is crash-free at loglevel 4
with the fix.

Issue: #2062
Fixes #5618
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i#2062 memtrace nonmod part 2: Raw2trace parsing of encoding file DynamoRIO/dynamorio
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@derekbruening