`libdl.so` not found in search path and causes a crash

[vadi2]

Description

Trying out the .NET 6 preview 4, I'm not able to run my application anymore due to a crash.

Configuration

• .NET 6 preview 4 installed from snap
• Ubuntu 20.04 LTS, x64

Regression?

Worked on .NET 5, so yes.

Other information

Running the app itself gives a segfault:

/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer
Qt runtime not present in /media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/qt-runtime, using a default one
Segmentation fault (core dumped)

GDB shows that it's an issue with dlopen:

(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x00007f00526c334c in dlopen_doit (a=0x7ffecd916bd0) at dlopen.c:66
#2  0x00007f0062d8a1ef in _dl_catch_exception () from /snap/core18/current/lib/x86_64-linux-gnu/libc.so.6
#3  0x00007f0062d8a27f in _dl_catch_error () from /snap/core18/current/lib/x86_64-linux-gnu/libc.so.6
#4  0x00007f00526c3b59 in _dlerror_run (operate=operate@entry=0x7f00526c32f0 <dlopen_doit>, args=args@entry=0x7ffecd916bd0) at dlerror.c:170
#5  0x00007f00526c33da in __dlopen (file=<optimized out>, mode=<optimized out>) at dlopen.c:87
#6  0x00007effe92c4895 in ?? ()
#7  0x00007ffecd916c10 in ?? ()
#8  0x00000000000b12b7 in ?? ()
#9  0x00007f0062aec3f0 in ?? () from /snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/libcoreclr.so
#10 0xffffffffffffffff in ?? ()
#11 0x00007effe9899598 in ?? ()

strace shows that it's trying to find libdl.so in all places except where it actually is (/lib/x86_64-linux-gnu/libdl.so.2):

openat(AT_FDCWD, "/home/vadi/.qmlnet-qt-runtimes/qt-5.15.1-7fc8b10-linux-x64/qt/lib/preload.txt", O_RDONLY|O_CLOEXEC) = 39
fstat(39, {st_mode=S_IFREG|0664, st_size=91, ...}) = 0
flock(39, LOCK_SH|LOCK_NB)              = 0
fadvise64(39, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
lseek(39, 0, SEEK_CUR)                  = 0
read(39, "libQt5QuickControls2.so.5\nlibQt5"..., 4096) = 91
read(39, "", 4096)                      = 0
flock(39, LOCK_UN)                      = 0
close(39)                               = 0
mprotect(0x7f5ac4185000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4185000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac4186000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4186000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac4179000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4179000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac3bb4000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac3bb4000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac3bb4000, 4096, PROT_READ|PROT_WRITE|PROT_EXEC) = 0
mprotect(0x7f5ac4187000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4187000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac4188000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4188000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac417a000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac417a000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac4189000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4189000, 4096, MADV_DODUMP) = 0
openat(AT_FDCWD, "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/runtimes/linux-x64/native/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/../../../usr/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/../../../lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/core18/current/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/core18/current/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 39
fstat(39, {st_mode=S_IFREG|0644, st_size=113889, ...}) = 0
mmap(NULL, 113889, PROT_READ, MAP_PRIVATE, 39, 0) = 0x7f5b33bce000
close(39)                               = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/lib/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
munmap(0x7f5b33bce000, 113889)          = 0
openat(AT_FDCWD, "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/runtimes/linux-x64/native/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/../../../usr/lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/../../../lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/core18/current/lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/core18/current/lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 39
fstat(39, {st_mode=S_IFREG|0644, st_size=113889, ...}) = 0
mmap(NULL, 113889, PROT_READ, MAP_PRIVATE, 39, 0) = 0x7f5b33bce000
close(39)                               = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = 39
read(39, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0 \22\0\0\0\0\0\0"..., 832) = 832
fstat(39, {st_mode=S_IFREG|0644, st_size=18816, ...}) = 0
mmap(NULL, 20752, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 39, 0) = 0x7f5b33bc8000
mmap(0x7f5b33bc9000, 8192, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 39, 0x1000) = 0x7f5b33bc9000
mmap(0x7f5b33bcb000, 4096, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 39, 0x3000) = 0x7f5b33bcb000
mmap(0x7f5b33bcc000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 39, 0x3000) = 0x7f5b33bcc000
close(39)                               = 0
mprotect(0x7f5b33bcc000, 4096, PROT_READ) = 0
munmap(0x7f5b33bce000, 113889)          = 0
futex(0x7f5b33bcd0c8, FUTEX_WAKE_PRIVATE, 2147483647) = 0
mprotect(0x7f5ac417b000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac417b000, 4096, MADV_DODUMP) = 0
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=NULL} ---
rt_sigprocmask(SIG_UNBLOCK, [RT_2], NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [SEGV], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [RT_2], NULL, 8) = 0
rt_sigaction(SIGSEGV, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f5b3e0a4980}, NULL, 8) = 0
unlink("/tmp/clr-debug-pipe-4901-4339-in") = 0
unlink("/tmp/clr-debug-pipe-4901-4339-out") = 0
unlink("/tmp/dotnet-diagnostic-4901-4339-socket") = 0
rt_sigreturn({mask=[]})                 = 0
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=NULL} ---
+++ killed by SIGSEGV (core dumped) +++
Segmentation fault (core dumped)

How to fix?

Tagging subscribers to this area: @carlossanlop
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

Trying out the .NET 6 preview 4, I'm not able to run my application anymore due to a crash.

Configuration

• .NET 6 preview 4 installed from snap
• Ubuntu 20.04 LTS, x64

Regression?

Worked on .NET 5, so yes.

Other information

Running the app itself gives a segfault:

/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer
Qt runtime not present in /media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/qt-runtime, using a default one
Segmentation fault (core dumped)

GDB shows that it's an issue with dlopen:

(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x00007f00526c334c in dlopen_doit (a=0x7ffecd916bd0) at dlopen.c:66
#2  0x00007f0062d8a1ef in _dl_catch_exception () from /snap/core18/current/lib/x86_64-linux-gnu/libc.so.6
#3  0x00007f0062d8a27f in _dl_catch_error () from /snap/core18/current/lib/x86_64-linux-gnu/libc.so.6
#4  0x00007f00526c3b59 in _dlerror_run (operate=operate@entry=0x7f00526c32f0 <dlopen_doit>, args=args@entry=0x7ffecd916bd0) at dlerror.c:170
#5  0x00007f00526c33da in __dlopen (file=<optimized out>, mode=<optimized out>) at dlopen.c:87
#6  0x00007effe92c4895 in ?? ()
#7  0x00007ffecd916c10 in ?? ()
#8  0x00000000000b12b7 in ?? ()
#9  0x00007f0062aec3f0 in ?? () from /snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/libcoreclr.so
#10 0xffffffffffffffff in ?? ()
#11 0x00007effe9899598 in ?? ()

strace shows that it's trying to find libdl.so in all places except where it actually is (/lib/x86_64-linux-gnu/libdl.so.2):

openat(AT_FDCWD, "/home/vadi/.qmlnet-qt-runtimes/qt-5.15.1-7fc8b10-linux-x64/qt/lib/preload.txt", O_RDONLY|O_CLOEXEC) = 39
fstat(39, {st_mode=S_IFREG|0664, st_size=91, ...}) = 0
flock(39, LOCK_SH|LOCK_NB)              = 0
fadvise64(39, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
lseek(39, 0, SEEK_CUR)                  = 0
read(39, "libQt5QuickControls2.so.5\nlibQt5"..., 4096) = 91
read(39, "", 4096)                      = 0
flock(39, LOCK_UN)                      = 0
close(39)                               = 0
mprotect(0x7f5ac4185000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4185000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac4186000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4186000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac4179000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4179000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac3bb4000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac3bb4000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac3bb4000, 4096, PROT_READ|PROT_WRITE|PROT_EXEC) = 0
mprotect(0x7f5ac4187000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4187000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac4188000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4188000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac417a000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac417a000, 4096, MADV_DODUMP) = 0
mprotect(0x7f5ac4189000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac4189000, 4096, MADV_DODUMP) = 0
openat(AT_FDCWD, "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/runtimes/linux-x64/native/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/../../../usr/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/../../../lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/core18/current/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/core18/current/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 39
fstat(39, {st_mode=S_IFREG|0644, st_size=113889, ...}) = 0
mmap(NULL, 113889, PROT_READ, MAP_PRIVATE, 39, 0) = 0x7f5b33bce000
close(39)                               = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/lib/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/dl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
munmap(0x7f5b33bce000, 113889)          = 0
openat(AT_FDCWD, "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/runtimes/linux-x64/native/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/../../../usr/lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/dotnet-sdk/127/shared/Microsoft.NETCore.App/6.0.0-preview.4.21253.7/../../../lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/core18/current/lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/snap/core18/current/lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 39
fstat(39, {st_mode=S_IFREG|0644, st_size=113889, ...}) = 0
mmap(NULL, 113889, PROT_READ, MAP_PRIVATE, 39, 0) = 0x7f5b33bce000
close(39)                               = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = 39
read(39, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0 \22\0\0\0\0\0\0"..., 832) = 832
fstat(39, {st_mode=S_IFREG|0644, st_size=18816, ...}) = 0
mmap(NULL, 20752, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 39, 0) = 0x7f5b33bc8000
mmap(0x7f5b33bc9000, 8192, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 39, 0x1000) = 0x7f5b33bc9000
mmap(0x7f5b33bcb000, 4096, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 39, 0x3000) = 0x7f5b33bcb000
mmap(0x7f5b33bcc000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 39, 0x3000) = 0x7f5b33bcc000
close(39)                               = 0
mprotect(0x7f5b33bcc000, 4096, PROT_READ) = 0
munmap(0x7f5b33bce000, 113889)          = 0
futex(0x7f5b33bcd0c8, FUTEX_WAKE_PRIVATE, 2147483647) = 0
mprotect(0x7f5ac417b000, 4096, PROT_READ|PROT_WRITE) = 0
madvise(0x7f5ac417b000, 4096, MADV_DODUMP) = 0
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=NULL} ---
rt_sigprocmask(SIG_UNBLOCK, [RT_2], NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [SEGV], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [RT_2], NULL, 8) = 0
rt_sigaction(SIGSEGV, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=SA_RESTORER, sa_restorer=0x7f5b3e0a4980}, NULL, 8) = 0
unlink("/tmp/clr-debug-pipe-4901-4339-in") = 0
unlink("/tmp/clr-debug-pipe-4901-4339-out") = 0
unlink("/tmp/dotnet-diagnostic-4901-4339-socket") = 0
rt_sigreturn({mask=[]})                 = 0
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=NULL} ---
+++ killed by SIGSEGV (core dumped) +++
Segmentation fault (core dumped)

How to fix?

Author:	vadi2
Assignees:	-
Labels:	area-System.IO, untriaged
Milestone:	-

[janvorli]

Looking at the dump above, I can see that it has succeeded loading the libdl:
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libdl.so", O_RDONLY|O_CLOEXEC) = 39
It looks like the problem is elsewhere. @vadi2 would you be able to run it under lldb and get a stack trace so that the location where the SIGSEGV happened can be identified?
If you are not familiar with lldb, the stack trace command is bt. If there are any private details in the stack trace, please feel free to remove them. But it looks like this is crashing at an early initialization time, so I guess only .NET frames would be on the stack.

[vadi2]

You're right, thanks for spotting that libdl.so does load.

lldb shows the following:

✦ ❯ lldb /media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer
(lldb) target create "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer"
Current executable set to '/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer' (x86_64).
(lldb) run
Process 83804 launched: '/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer' (x86_64)
Qt runtime not present in /media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/qt-runtime, using a default one
Process 83804 stopped
* thread #1, name = 'Hammer', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
    frame #0: 0x0000000000000000
error: memory read failed for 0x0
(lldb) bt
* thread #1, name = 'Hammer', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
  * frame #0: 0x0000000000000000
    frame #1: 0x00007ffff42a834c libdl.so`___lldb_unnamed_symbol5$$libdl.so + 92
    frame #2: 0x00007ffff6f8f1ef libc.so.6`_dl_catch_exception + 111
    frame #3: 0x00007ffff6f8f27f libc.so.6`_dl_catch_error + 47
    frame #4: 0x00007ffff42a8b59 libdl.so`___lldb_unnamed_symbol12$$libdl.so + 105
    frame #5: 0x00007ffff42a83da libdl.so`dlopen + 74
    frame #6: 0x00007fff7d5b4895
    frame #7: 0x00007fff7d5b475b
    frame #8: 0x00007fff7d5b4708
    frame #9: 0x00007fff7d5b43d2
    frame #10: 0x00007fff7d5b4334
    frame #11: 0x00007fff7d5b42e8
    frame #12: 0x00007fff7d5b2b2c
    frame #13: 0x00007fff7d5b0d05
    frame #14: 0x00007fff7d5a0c79
    frame #15: 0x00007ffff6a7b3e7 libcoreclr.so`___lldb_unnamed_symbol9554$$libcoreclr.so + 124
    frame #16: 0x00007ffff68cf63b libcoreclr.so`___lldb_unnamed_symbol4301$$libcoreclr.so + 1643
    frame #17: 0x00007ffff67a1d0b libcoreclr.so`___lldb_unnamed_symbol298$$libcoreclr.so + 923
    frame #18: 0x00007ffff67a2039 libcoreclr.so`___lldb_unnamed_symbol299$$libcoreclr.so + 393
    frame #19: 0x00007ffff67e1423 libcoreclr.so`___lldb_unnamed_symbol1150$$libcoreclr.so + 627
    frame #20: 0x00007ffff678a90d libcoreclr.so`coreclr_execute_assembly + 413
    frame #21: 0x00007ffff7f216e1 libhostpolicy.so`___lldb_unnamed_symbol160$$libhostpolicy.so + 1345
    frame #22: 0x00007ffff7f21b71 libhostpolicy.so`___lldb_unnamed_symbol161$$libhostpolicy.so + 49
    frame #23: 0x00007ffff7f2259c libhostpolicy.so`corehost_main + 172
    frame #24: 0x00007ffff7f7e2a9 libhostfxr.so`___lldb_unnamed_symbol95$$libhostfxr.so + 1817
    frame #25: 0x00007ffff7f7c9ab libhostfxr.so`___lldb_unnamed_symbol93$$libhostfxr.so + 667
    frame #26: 0x00007ffff7f77e9b libhostfxr.so`hostfxr_main_startupinfo + 171
    frame #27: 0x0000555555564545 Hammer`___lldb_unnamed_symbol152$$Hammer + 1045
    frame #28: 0x0000555555564a10 Hammer`___lldb_unnamed_symbol153$$Hammer + 144
    frame #29: 0x00007ffff6e49bf7 libc.so.6`__libc_start_main + 231
    frame #30: 0x0000555555558d8a Hammer`___lldb_unnamed_symbol33$$Hammer + 41
(lldb) 

[janvorli]

We will need to get symbols for the libdl.so and libc6 to see more. Can you please install libc6-dbg Ubuntu package and try again? lldb should see the symbols then. If not, we may need to point it to the debug symbols directory.

[vadi2]

It seems it's already installed. How to point it to the symbols?

✦ ❯ sudo apt install libc6-dbg
[sudo] password for vadi: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libc6-dbg is already the newest version (2.31-0ubuntu9.2).
libc6-dbg set to manually installed.
0 upgraded, 0 newly installed, 0 to remove and 16 not upgraded.

~ took 2s 
✦ ❯ lldb /media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer
(lldb) target create "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer"
Current executable set to '/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer' (x86_64).
(lldb) run
Process 194011 launched: '/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer' (x86_64)
Qt runtime not present in /media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/qt-runtime, using a default one
Process 194011 stopped
* thread #1, name = 'Hammer', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
    frame #0: 0x0000000000000000
error: memory read failed for 0x0
(lldb) bt
* thread #1, name = 'Hammer', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
  * frame #0: 0x0000000000000000
    frame #1: 0x00007ffff42a834c libdl.so`___lldb_unnamed_symbol5$$libdl.so + 92
    frame #2: 0x00007ffff6f8f1ef libc.so.6`_dl_catch_exception + 111
    frame #3: 0x00007ffff6f8f27f libc.so.6`_dl_catch_error + 47
    frame #4: 0x00007ffff42a8b59 libdl.so`___lldb_unnamed_symbol12$$libdl.so + 105
    frame #5: 0x00007ffff42a83da libdl.so`dlopen + 74
    frame #6: 0x00007fff7d5c4895
    frame #7: 0x00007fff7d5c475b
    frame #8: 0x00007fff7d5c4708
    frame #9: 0x00007fff7d5c43d2
    frame #10: 0x00007fff7d5c4334
    frame #11: 0x00007fff7d5c42e8
    frame #12: 0x00007fff7d5c2b2c
    frame #13: 0x00007fff7d5c0d05
    frame #14: 0x00007fff7d5b0c79
    frame #15: 0x00007ffff6a7b3e7 libcoreclr.so`___lldb_unnamed_symbol9554$$libcoreclr.so + 124
    frame #16: 0x00007ffff68cf63b libcoreclr.so`___lldb_unnamed_symbol4301$$libcoreclr.so + 1643
    frame #17: 0x00007ffff67a1d0b libcoreclr.so`___lldb_unnamed_symbol298$$libcoreclr.so + 923
    frame #18: 0x00007ffff67a2039 libcoreclr.so`___lldb_unnamed_symbol299$$libcoreclr.so + 393
    frame #19: 0x00007ffff67e1423 libcoreclr.so`___lldb_unnamed_symbol1150$$libcoreclr.so + 627
    frame #20: 0x00007ffff678a90d libcoreclr.so`coreclr_execute_assembly + 413
    frame #21: 0x00007ffff7f216e1 libhostpolicy.so`___lldb_unnamed_symbol160$$libhostpolicy.so + 1345
    frame #22: 0x00007ffff7f21b71 libhostpolicy.so`___lldb_unnamed_symbol161$$libhostpolicy.so + 49
    frame #23: 0x00007ffff7f2259c libhostpolicy.so`corehost_main + 172
    frame #24: 0x00007ffff7f7e2a9 libhostfxr.so`___lldb_unnamed_symbol95$$libhostfxr.so + 1817
    frame #25: 0x00007ffff7f7c9ab libhostfxr.so`___lldb_unnamed_symbol93$$libhostfxr.so + 667
    frame #26: 0x00007ffff7f77e9b libhostfxr.so`hostfxr_main_startupinfo + 171
    frame #27: 0x0000555555564545 Hammer`___lldb_unnamed_symbol152$$Hammer + 1045
    frame #28: 0x0000555555564a10 Hammer`___lldb_unnamed_symbol153$$Hammer + 144
    frame #29: 0x00007ffff6e49bf7 libc.so.6`__libc_start_main + 231
    frame #30: 0x0000555555558d8a Hammer`___lldb_unnamed_symbol33$$Hammer + 41
(lldb) 

[janvorli]

can you please try the following lldb commands before executing the bt?

target symbols add /usr/lib/debug/lib/x86_64-linux-gnu/libdl-2.31.so
target symbols add /usr/lib/debug/lib/x86_64-linux-gnu/libc-2.31.so

[vadi2]

Sure, here it is:

✦ ❯ lldb /media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer
(lldb) target create "/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer"
Current executable set to '/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer' (x86_64).
(lldb) run
Process 416270 launched: '/media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/Hammer' (x86_64)
Qt runtime not present in /media/vadi/SSDer/Programs/Hammer/bin/Debug/net6.0/qt-runtime, using a default one
Process 416270 stopped
* thread #1, name = 'Hammer', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
    frame #0: 0x0000000000000000
error: memory read failed for 0x0
(lldb) target symbols add /usr/lib/debug/lib/x86_64-linux-gnu/libdl-2.31.so
symbol file '/usr/lib/debug/lib/x86_64-linux-gnu/libdl-2.31.so' has been added to '/lib/x86_64-linux-gnu/libdl.so'
(lldb) target symbols add /usr/lib/debug/lib/x86_64-linux-gnu/libc-2.31.so
error: symbol file '/usr/lib/debug/lib/x86_64-linux-gnu/libc-2.31.so' does not match any existing module
(lldb) bt
* thread #1, name = 'Hammer', stop reason = signal SIGSEGV: invalid address (fault address: 0x0)
  * frame #0: 0x0000000000000000
    frame #1: 0x00007ffff42a834c libdl.so`dlopen_doit(a=0x00007fffffffca80) at dlopen.c:66:15
    frame #2: 0x00007ffff6f8f1ef libc.so.6`_dl_catch_exception + 111
    frame #3: 0x00007ffff6f8f27f libc.so.6`_dl_catch_error + 47
    frame #4: 0x00007ffff42a8b59 libdl.so`_dlerror_run(operate=(libdl.so`dlopen_doit at dlopen.c:58:1), args=0x00007fffffffca80) at dlerror.c:170:21
    frame #5: 0x00007ffff42a83da libdl.so`__dlopen(file=<unavailable>, mode=<unavailable>) at dlopen.c:87:10
    frame #6: 0x00007fff7d5a4895
    frame #7: 0x00007fff7d5a475b
    frame #8: 0x00007fff7d5a4708
    frame #9: 0x00007fff7d5a43d2
    frame #10: 0x00007fff7d5a4334
    frame #11: 0x00007fff7d5a42e8
    frame #12: 0x00007fff7d5a2b2c
    frame #13: 0x00007fff7d5a0d05
    frame #14: 0x00007fff7d590c79
    frame #15: 0x00007ffff6a7b3e7 libcoreclr.so`___lldb_unnamed_symbol9554$$libcoreclr.so + 124
    frame #16: 0x00007ffff68cf63b libcoreclr.so`___lldb_unnamed_symbol4301$$libcoreclr.so + 1643
    frame #17: 0x00007ffff67a1d0b libcoreclr.so`___lldb_unnamed_symbol298$$libcoreclr.so + 923
    frame #18: 0x00007ffff67a2039 libcoreclr.so`___lldb_unnamed_symbol299$$libcoreclr.so + 393
    frame #19: 0x00007ffff67e1423 libcoreclr.so`___lldb_unnamed_symbol1150$$libcoreclr.so + 627
    frame #20: 0x00007ffff678a90d libcoreclr.so`coreclr_execute_assembly + 413
    frame #21: 0x00007ffff7f216e1 libhostpolicy.so`___lldb_unnamed_symbol160$$libhostpolicy.so + 1345
    frame #22: 0x00007ffff7f21b71 libhostpolicy.so`___lldb_unnamed_symbol161$$libhostpolicy.so + 49
    frame #23: 0x00007ffff7f2259c libhostpolicy.so`corehost_main + 172
    frame #24: 0x00007ffff7f7e2a9 libhostfxr.so`___lldb_unnamed_symbol95$$libhostfxr.so + 1817
    frame #25: 0x00007ffff7f7c9ab libhostfxr.so`___lldb_unnamed_symbol93$$libhostfxr.so + 667
    frame #26: 0x00007ffff7f77e9b libhostfxr.so`hostfxr_main_startupinfo + 171
    frame #27: 0x0000555555564545 Hammer`___lldb_unnamed_symbol152$$Hammer + 1045
    frame #28: 0x0000555555564a10 Hammer`___lldb_unnamed_symbol153$$Hammer + 144
    frame #29: 0x00007ffff6e49bf7 libc.so.6`__libc_start_main + 231
    frame #30: 0x0000555555558d8a Hammer`___lldb_unnamed_symbol33$$Hammer + 41
(lldb) 

[janvorli]

Ok, great. Can you please run these lldb commands?

f 1
disass -a $rip

[vadi2]

(lldb) f 1
frame #1: 0x00007ffff42a834c libdl.so`dlopen_doit(a=0x00007fffffffca80) at dlopen.c:66:15
(lldb) disass -a $rip
libdl.so`dlopen_doit:
    0x7ffff42a82f0 <+0>:   endbr64 
    0x7ffff42a82f4 <+4>:   pushq  %rbx
    0x7ffff42a82f5 <+5>:   movl   0x8(%rdi), %esi
    0x7ffff42a82f8 <+8>:   testl  $0xbfffeef0, %esi         ; imm = 0xBFFFEEF0 
    0x7ffff42a82fe <+14>:  jne    0x7ffff42a8364            ; <+116> [inlined] dlopen_doit at dlopen.c:57
    0x7ffff42a8300 <+16>:  movq   0x3cd1(%rip), %rdx
    0x7ffff42a8307 <+23>:  movq   %rdi, %rbx
    0x7ffff42a830a <+26>:  movq   0x3caf(%rip), %rax
    0x7ffff42a8311 <+33>:  orl    $0x80000000, %esi         ; imm = 0x80000000 
    0x7ffff42a8317 <+39>:  movq   (%rdi), %rdi
    0x7ffff42a831a <+42>:  movq   0x3ddf(%rip), %r9         ; __dlfcn_argv
    0x7ffff42a8321 <+49>:  movq   $-0x2, %r10
    0x7ffff42a8328 <+56>:  movq   (%rdx), %rcx
    0x7ffff42a832b <+59>:  movq   0x1e8(%rax), %rax
    0x7ffff42a8332 <+66>:  movl   0x3dcf(%rip), %r8d        ; __dlfcn_argc
    0x7ffff42a8339 <+73>:  movq   0x18(%rbx), %rdx
    0x7ffff42a833d <+77>:  testq  %rdi, %rdi
    0x7ffff42a8340 <+80>:  je     0x7ffff42a8358            ; <+104> at dlopen.c:66:15
    0x7ffff42a8342 <+82>:  subq   $0x8, %rsp
    0x7ffff42a8346 <+86>:  pushq  %rcx
    0x7ffff42a8347 <+87>:  movq   %r10, %rcx
    0x7ffff42a834a <+90>:  callq  *%rax
->  0x7ffff42a834c <+92>:  movq   %rax, 0x10(%rbx)
    0x7ffff42a8350 <+96>:  popq   %rax
    0x7ffff42a8351 <+97>:  popq   %rdx
    0x7ffff42a8352 <+98>:  popq   %rbx
    0x7ffff42a8353 <+99>:  retq   
    0x7ffff42a8354 <+100>: nopl   (%rax)
    0x7ffff42a8358 <+104>: xorl   %r10d, %r10d
    0x7ffff42a835b <+107>: leaq   0x1cc5(%rip), %rdi
    0x7ffff42a8362 <+114>: jmp    0x7ffff42a8342            ; <+82> at dlopen.c:66:15
    0x7ffff42a8364 <+116>: movq   0x3c65(%rip), %rdi
    0x7ffff42a836b <+123>: movl   $0x5, %edx
    0x7ffff42a8370 <+128>: leaq   0x1c89(%rip), %rsi
    0x7ffff42a8377 <+135>: callq  0x7ffff42a81b0
    0x7ffff42a837c <+140>: xorl   %edx, %edx
    0x7ffff42a837e <+142>: xorl   %esi, %esi
    0x7ffff42a8380 <+144>: xorl   %edi, %edi
    0x7ffff42a8382 <+146>: movq   %rax, %rcx
    0x7ffff42a8385 <+149>: callq  0x7ffff42a81c0
(lldb) 

[janvorli]

Thank you, now the following please:

x/gx 0x7ffff42a8311+0x3caf

[janvorli]

(I am trying to find out where the callq *rax would go)

[vadi2]

Yep sure - it says:

(lldb) x/gx 0x7ffff42a8311+0x3caf
0x7ffff42abfc0: 0x00007ffff7ffc760
(lldb) 

[janvorli]

Ok, so now:

x/gx 0x00007ffff7ffc760+0x1e8