>Synopsis: SIGSEGV in
>libunwind::UnwindInfoSectionsCache::CacheTree_RB_INSERT_COLOR
>Category: library
>Environment:
System : OpenBSD 6.7
Details : OpenBSD 6.7 (GENERIC.MP) #182: Thu May 7 11:11:58 MDT
2020
[email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
Architecture: OpenBSD.amd64
Machine : amd64
>Description:
[clang++] During a long-running stress test for exceptions inside threads
a segfault occurs in libunwind. eg++ does not exhibit the problem.
(gdb) bt
#0 0x00000c75b159cca4 in
libunwind::UnwindInfoSectionsCache::CacheTree_RB_INSERT_COLOR
(this=0xc75b15c1248 <libunwind::uwis_cache>, head=0xc75b15c1250
<libunwind::uwis_cache+8>, elm=0x0)
at /usr/src/lib/libcxxabi/../libunwind/src/AddressSpace.hpp:234
#1 0x00000c75b1599eaa in
libunwind::UnwindInfoSectionsCache::CacheTree_RB_INSERT (this=<optimized out>,
head=<optimized out>, elm=<optimized out>)
at /usr/src/lib/libcxxabi/../libunwind/src/AddressSpace.hpp:234
#2 libunwind::UnwindInfoSectionsCache::setUnwindInfoSectionsForPC
(this=<optimized out>, key=<optimized out>, uis=...) at
/usr/src/lib/libcxxabi/../libunwind/src/AddressSpace.hpp:228
#3 libunwind::UnwindCursor<libunwind::LocalAddressSpace,
libunwind::Registers_x86_64>::setInfoBasedOnIPRegister (this=0xc767ebd50c8,
isReturnAddress=<optimized out>)
at /usr/src/lib/libcxxabi/../libunwind/src/UnwindCursor.hpp:1828
#4 0x00000c75b1599b7d in libunwind::UnwindCursor<libunwind::LocalAddressSpace,
libunwind::Registers_x86_64>::step (this=0xc767ebd50c8)
at /usr/src/lib/libcxxabi/../libunwind/src/UnwindCursor.hpp:1968
#5 0x00000c75b1598204 in unwind_phase1 (uc=0xc75b15a0af0
<__cxxabiv1::exception_cleanup_func(_Unwind_Reason_Code, _Unwind_Exception*)>,
cursor=0xc75b15bcdd8 <vtable for
libunwind::UnwindCursor<libunwind::LocalAddressSpace,
libunwind::Registers_x86_64>+16>, exception_object=0xc7638cc8960)
at /usr/src/lib/libcxxabi/../libunwind/src/UnwindLevel1.c:46
#6 _Unwind_RaiseException (exception_object=0xc7638cc8960) at
/usr/src/lib/libcxxabi/../libunwind/src/UnwindLevel1.c:357
#7 0x00000c75b15a0ae3 in __cxa_throw (thrown_object=0xc7638cc8980,
tinfo=0xc739df31078 <typeinfo for suntime_error>, dest=<optimized out>) at
/usr/src/lib/libcxxabi/src/cxa_exception.cpp:281
#8 0x00000c739df2f4c7 in doit () at test.cc:14
#9 0x00000c739df2f639 in std::__1::__invoke<void (*)()> (__f=<optimized out>)
at /usr/include/c++/v1/type_traits:4353
#10 std::__1::__thread_execute<std::__1::unique_ptr<std::__1::__thread_struct,
std::__1::default_delete<std::__1::__thread_struct> >, void
(*)()>(std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct,
std::__1::default_delete<std::__1::__thread_struct> >, void (*)()>&,
std::__1::__tuple_indices<>) (__t=...) at /usr/include/c++/v1/thread:342
#11
std::__1::__thread_proxy<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct,
std::__1::default_delete<std::__1::__thread_struct> >, void (*)()> >
(__vp=0xc760f757a40)
at /usr/include/c++/v1/thread:352
#12 0x00000c768afa30d1 in _rthread_start (v=<optimized out>) at
/usr/src/lib/librthread/rthread.c:96
#13 0x00000c7687359748 in __tfork_thread () at
/usr/src/lib/libc/arch/amd64/sys/tfork_thread.S:77
#14 0x0000000000000000 in ?? ()
>How-To-Repeat:
test.cc:
===============================================================================
#include <stdexcept>
#include <thread>
#include <vector>
class suntime_error : public std::runtime_error {
using std::runtime_error::runtime_error;
};
static void
doit()
{
try {
throw suntime_error("this is an error");
}
catch (const suntime_error& err) {
(void)err;
}
}
static void
do_threads()
{
const size_t n = 1000;
std::vector<std::thread> t(n);
for (size_t k = 0; k < n; k++) {
t[k] = std::thread(doit);
}
for (size_t k = 0; k < n; k++) {
t[k].join();
}
}
int
main()
{
do_threads();
return 0;
}
===============================================================================
doit.sh:
===============================================================================
#!/bin/sh
while ./test; do
:
done
===============================================================================
clang++ -pthread -Wall -Wextra -std=c++11 -pedantic -DNDEBUG -O2 -g -o test
test.cc
./doit.sh
Note that it can take between 1min and several hours to reproduce this issue.
dmesg:
OpenBSD 6.7 (GENERIC.MP) #182: Thu May 7 11:11:58 MDT 2020
[email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
real mem = 1056833536 (1007MB)
avail mem = 1012244480 (965MB)
mpath0 at root
scsibus0 at mpath0: 256 targets
mainbus0 at root
bios0 at mainbus0: SMBIOS rev. 2.8 @ 0xf64b0 (9 entries)
bios0: vendor SeaBIOS version "Ubuntu-1.8.2-1ubuntu1" date 04/01/2014
bios0: QEMU Standard PC (i440FX + PIIX, 1996)
acpi0 at bios0: ACPI 1.0
acpi0: sleep states S3 S4 S5
acpi0: tables DSDT FACP SSDT APIC HPET
acpi0: wakeup devices
acpitimer0 at acpi0: 3579545 Hz, 24 bits
acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: QEMU Virtual CPU version 2.5+, 4320.47 MHz, 06-06-03
cpu0:
FPU,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,MMX,FXSR,SSE,SSE2,SSE3,VMX,CX16,x2APIC,HV,NXE,LONG,LAHF,MELTDOWN
cpu0: 64KB 64b/line 2-way I-cache, 64KB 64b/line 2-way D-cache, 512KB 64b/line
16-way L2 cache
cpu0: ITLB 255 4KB entries direct-mapped, 255 4MB entries direct-mapped
cpu0: DTLB 255 4KB entries direct-mapped, 255 4MB entries direct-mapped
cpu0: smt 0, core 0, package 0
mtrr: Pentium Pro MTRR support, 8 var ranges, 88 fixed ranges
cpu0: apic clock running at 1230MHz
ioapic0 at mainbus0: apid 0 pa 0xfec00000, version 11, 24 pins
acpihpet0 at acpi0: 100000000 Hz
acpiprt0 at acpi0: bus 0 (PCI0)
acpicpu0 at acpi0: C1(@1 halt!)
"ACPI0006" at acpi0 not configured
acpipci0 at acpi0 PCI0: _OSC failed
acpicmos0 at acpi0
"PNP0A06" at acpi0 not configured
"PNP0A06" at acpi0 not configured
"PNP0A06" at acpi0 not configured
pvbus0 at mainbus0: KVM
pvclock0 at pvbus0
pci0 at mainbus0 bus 0
pchb0 at pci0 dev 0 function 0 "Intel 82441FX" rev 0x02
pcib0 at pci0 dev 1 function 0 "Intel 82371SB ISA" rev 0x00
pciide0 at pci0 dev 1 function 1 "Intel 82371SB IDE" rev 0x00: DMA, channel 0
wired to compatibility, channel 1 wired to compatibility
wd0 at pciide0 channel 0 drive 0: <QEMU HARDDISK>
wd0: 16-sector PIO, LBA48, 61440MB, 125829120 sectors
wd0(pciide0:0:0): using PIO mode 4, DMA mode 2
atapiscsi0 at pciide0 channel 1 drive 0
scsibus1 at atapiscsi0: 2 targets
cd0 at scsibus1 targ 0 lun 0: <QEMU, QEMU DVD-ROM, 2.5+> removable
cd0(pciide0:1:0): using PIO mode 4, DMA mode 2
piixpm0 at pci0 dev 1 function 3 "Intel 82371AB Power" rev 0x03: apic 0 int 9
iic0 at piixpm0
vga1 at pci0 dev 2 function 0 "Bochs VGA" rev 0x02
wsdisplay0 at vga1 mux 1: console (80x25, vt100 emulation)
wsdisplay0: screen 1-5 added (80x25, vt100 emulation)
em0 at pci0 dev 3 function 0 "Intel 82540EM" rev 0x03: apic 0 int 11, address
52:54:00:12:34:56
isa0 at pcib0
isadma0 at isa0
fdc0 at isa0 port 0x3f0/6 irq 6 drq 2
com0 at isa0 port 0x3f8/8 irq 4: ns16550a, 16 byte fifo
pckbc0 at isa0 port 0x60/5 irq 1 irq 12
pckbd0 at pckbc0 (kbd slot)
wskbd0 at pckbd0: console keyboard, using wsdisplay0
pms0 at pckbc0 (aux slot)
wsmouse0 at pms0 mux 0
pcppi0 at isa0 port 0x61
spkr0 at pcppi0
lpt0 at isa0 port 0x378/4 irq 7
vmm0 at mainbus0: VMX/EPT (using slow L1TF mitigation)
vscsi0 at root
scsibus2 at vscsi0: 256 targets
softraid0 at root
scsibus3 at softraid0: 256 targets
root on wd0a (8da2a562c9eb4344.a) swap on wd0b dump on wd0b
usbdevs:
usbdevs: no USB controllers found
