assert failure in signal.c

[Prasun Ratn]

I am seeing this assert failure. I am on commit 3c598ac8490e1c8b02b40563d8ced8066b2eabf9

Is this a bug or something weird manifesting in my local setup?

$ build/bin64/drrun -t drcachesim -trace_after_instrs 2000M --offline -- build/suite/tests/bin/pthreads.ptsig
<Starting application /home/prasun/dynamorio-latest/build/suite/tests/bin/pthreads.ptsig (246857)>
<Initial options = -no_dynamic_options -client_lib '/home/prasun/dynamorio-latest/build/bin64/../clients/lib64/debug/libdrmemtrace.so;0;-trace_after_instrs 2000M --offline' -client_lib64 '/home/prasun/dynamorio-latest/build/bin64/../clients/lib64/debug/libdrmemtrace.so;0;-trace_after_instrs 2000M --offline' -code_api -stack_size 56K -signal_stack_size 32K -max_elide_jmp 0 -max_elide_call 0 -early_inject -emulate_brk -no_inline_ignored_syscalls -native_exec_default_list '' -no_native_exec_managed_code -no_indcall2direct >
<Paste into GDB to debug DynamoRIO clients:
set confirm off
add-symbol-file '/home/prasun/dynamorio-latest/build/bin64/../clients/lib64/debug/libdrmemtrace.so' 0x00007fdd4ee8c3c0
add-symbol-file '/home/prasun/dynamorio-latest/build/lib64/debug/libdynamorio.so' 0x00007fdd930c27b8
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrsyms.so' 0x00007fdd4f11a260
add-symbol-file '/lib/x86_64-linux-gnu/libc.so.6' 0x00007fdd92a79360
add-symbol-file '/lib64/ld-linux-x86-64.so.2' 0x00007fdd9282bf10
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrwrap.so' 0x00007fdd4f3626d0
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrmgr.so' 0x00007fdd4f573090
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrutil.so' 0x00007fdd4f782850
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrstatecmp.so' 0x00007fdd4f9887b0
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrcovlib.so' 0x00007fdd4fb8ee60
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrx.so' 0x00007fdd4fd9b350
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrreg.so' 0x00007fdd4ffae010
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrbbdup.so' 0x00007fdd501bd330
add-symbol-file '/home/prasun/dynamorio-latest/build/ext/lib64/debug/libdrpttracer.so' 0x00007fdd503ca130
add-symbol-file '/usr/lib/x86_64-linux-gnu/libsnappy.so.1' 0x00007fdd926241b0
add-symbol-file '/usr/lib/x86_64-linux-gnu/libstdc++.so.6' 0x00007fdd922b09c0
add-symbol-file '/lib/x86_64-linux-gnu/libm.so.6' 0x00007fdd91e80a80
add-symbol-file '/lib/libgcc_s.so.1' 0x00007fdd91c5eb50
add-symbol-file '/lib/x86_64-linux-gnu/libz.so.1' 0x00007fdd91a3ff90
>
<curiosity: rex.w on OPSZ_6_irex10_short4!>
<(1+x) Handling our fault in a TRY at 0x00007fdd93329228>
<failed to translate>
<Application /home/prasun/dynamorio-latest/build/suite/tests/bin/pthreads.ptsig (246857).  Internal Error: DynamoRIO debug check failure: /home/prasun/dynamorio-latest/dynamorio/core/unix/signal.c:3118 false
(Error occurred @2310 frags in tid 246857)
version 9.0.19345, custom build
-no_dynamic_options -client_lib '/home/prasun/dynamorio-latest/build/bin64/../clients/lib64/debug/libdrmemtrace.so;0;-trace_after_instrs 2000M --offline' -client_lib64 '/home/prasun/dynamorio-latest/build/bin64/../clients/lib64/debug/libdrmemtrace.so;0;-trace_after_instrs 2000M --offline' -code_api -stack_size 56K -signa
0x00007fdb4ef3ec40 0x00007fdd9315d5fc
0x00007fdb4ef3ee90 0x00007fdd933641aa
0x00007fdb4ef3f7d0 0x00007fdd9336a958
0x00007fdb4ef3fa10 0x00007fdd9336de31
0x00007fdb4ef3fab0 0x00007fdd93328d49
0x00007ffce2340bf0 0x00007fdd91420c87
0x00007fdd8ee73710 0x158e258d4c544155
/home/prasun/dynamorio-latest/build/lib64/debug/libdynamorio.so=0x00007fdd93077000
/home/prasun/dynamorio-latest/build/bin64/../clients/lib64/debug/libdrmemtrace.so=0x00007fdd4ee79000
/lib/x86_64-linux-gnu/libz.so.1=0x00007fdd91a3e000
/usr/lib/x86_64-linux-gnu/libsnappy.so.1=0x00007fdd92622000
/usr/lib/x86_64-linux-gnu/libstdc++.so.6=0x00007fdd92214000
/lib/libgcc_s.so.1=0x00007fdd91c5c000
/lib/x86_64-linux-gnu/libm.so.6=0x00007fdd91e75000
/home>

[Derek Bruening]

Probably a bug.  I would suggest geting a symbolic callstack and trying to understand why it is translating and why it failed.

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[Prasun Ratn]

Looks like there is a segv caused by the code below and the assert failure happens later.

  0x00007f7298058dcb  b8 2a 00 00 00       mov    $0x0000002a -> %eax
  0x00007f7298058dd0  c7 00 00 00 00 00    mov    $0x00000000 -> (%rax)[4byte]

computing memory target for 0x00007f7298058dd0 causing SIGSEGV, kernel claims it is 0x000000000000002a
compute_memory_target: falling back to racy protection checks
opnd_compute_address for: (%rax)
    base => 0x000000000000002a
    index,scale => 0x000000000000002a
    disp => 0x000000000000002a
For SIGSEGV at cache pc 0x00007f7298058dd0, computed target write 0x000000000000002a
    faulting instr: mov    $0x00000000 -> (%rax)[4byte]
** Received SIGSEGV at cache pc 0x00007f7298058dd0 in thread 250275
record_pending_signal(11) from cache pc 0x00007f7298058dd0
    not certain can delay so handling now
    action is not SIG_IGN
    retaddr = 0x00007f72dabe0d49
SYSLOG_WARNING: failed to translate
SYSLOG_ERROR: Application /home/prasun/dynamorio-latest/build/suite/tests/bin/pthreads.ptsig (250275).  Internal Error: DynamoRIO debug check failure: /home/prasun/dynamorio-latest/dynamorio/core/unix/signal.c:3118 false

gdb output

Thread 1 "pthreads.ptsig" received signal SIGSEGV, Segmentation fault.
0x00007fffb5677d90 in ?? ()
(gdb) refresh
(gdb) c
Continuing.
<failed to translate>

Thread 1 "pthreads.ptsig" hit Breakpoint 1, translate_sigcontext (dcontext=0x7ffdb3de0080, uc=0x7ffdb3e16ac0, avoid_failure=true, f=0x7ffdb4004158)
    at /home/prasun/dynamorio-latest/dynamorio/core/unix/signal.c:3118
(gdb) where
#0  translate_sigcontext (dcontext=0x7ffdb3de0080, uc=0x7ffdb3e16ac0, avoid_failure=true, f=0x7ffdb4004158) at /home/prasun/dynamorio-latest/dynamorio/core/unix/signal.c:3118
#1  0x00000000712f3958 in record_pending_signal (dcontext=0x7ffdb3de0080, sig=11, ucxt=0x7ffdb3e16ac0, frame=0x7ffdb3e16ab8, forged=false, access_address=0x2a <error: Cannot access memory at address 0x2a>)
    at /home/prasun/dynamorio-latest/dynamorio/core/unix/signal.c:5051
#2  0x00000000712f6e31 in main_signal_handler_C (sig=11, siginfo=0x7ffdb3e16bf0, ucxt=0x7ffdb3e16ac0, xsp=0x7ffdb3e16ab8 "I\035+q") at /home/prasun/dynamorio-latest/dynamorio/core/unix/signal.c:5994
#3  0x00000000712b1d49 in xfer_to_new_libdr () at /home/prasun/dynamorio-latest/dynamorio/core/arch/x86/x86.asm:1203
#4  0x0000000000000007 in ?? ()
#5  0x0000000000000000 in ?? ()

[Derek Bruening]

Did you check the sources?  Dereference of 42 is probably quite deliberate. So it’s just the translation assert that is unexpected. Logs can help figure out why.