[Bug gdb/30255] New: GDB on Windows cannot retrieve a stacktrace when a NULL function pointer is called

["luca.bacci at outlook dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=30255

            Bug ID: 30255
           Summary: GDB on Windows cannot retrieve a stacktrace when a
                    NULL function pointer is called
           Product: gdb
           Version: 13.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: luca.bacci at outlook dot com
  Target Milestone: ---

Hello, I use gdb on MSYS2 to fix issues with GIMP, Inkscape etc on Windows. One
thing I noticed is that gdb is unable to give a stacktrace anytime the debugged
program invokes a NULL function pointer. For example, consider:

void (*func_ptr)(void);

static void a (void)
{
  func_ptr ();
}

static void b (void)
{
  a ();
}

static void c (void)
{
  b ();
}

int main() {
  c ();
}

When running under GDB 13.1 the stacktrace is not retrieved:

$ gcc -g -o sample sample.c
$ gdb ./sample.exe 
GNU gdb (GDB) 13.1
Copyright (C) 2023 Free Software Foundation, Inc.
Reading symbols from ./sample.exe...
(gdb) r
Starting program: D:\sample.exe 
[New Thread 27612.0x6ec0]

Thread 1 received signal SIGSEGV, Segmentation fault.
0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb)

I have tried with lldb and it works:

$ lldb ./sample.exe 
(lldb) target create "./sample.exe"
(rrent executable set to 'D:\sample.exe' (x86_64).
(lldb) r
(lldb) Process 23036 launched: 'D:\sample.exe' (x86_64)
Process 23036 stopped
* thread #1, stop reason = Exception 0xc0000005 encountered at address
0x000000: User-mode data execution prevention (DEP) violation at location
0x00000000
    frame #0: 0x0000000000000000
error: Only part of a ReadProcessMemory or WriteProcessMemory request was
completed.
(lldb) bt
* thread #1, stop reason = Exception 0xc0000005 encountered at address
0x000000: User-mode data execution prevention (DEP) violation at location
0x00000000
  * frame #0: 0x0000000000000000
    frame #1: 0x00007ff73e2813ea sample.exe`a at sample.c:5:3
    frame #2: 0x00007ff73e2813d9 sample.exe`b at sample.c:10:3
    frame #3: 0x00007ff73e2813c9 sample.exe`c at sample.c:15:3
    frame #4: 0x00007ff73e2813b4 sample.exe`main at sample.c:19:3
    frame #5: 0x00007ff73e281316 sample.exe`__tmainCRTStartup at
crtexe.c:272:15
    frame #6: 0x00007ff73e281366 sample.exe`mainCRTStartup at crtexe.c:193:9
    frame #7: 0x00007ff90dff7614 kernel32.dll`BaseThreadInitThunk + 20
    frame #8: 0x00007ff90f1a26a1 ntdll.dll`RtlUserThreadStart + 33
(lldb)

See also: https://gitlab.com/inkscape/inkscape/-/issues/4031#note_1231250877,
where we encountered this issue due to libepoxy returning NULL function
pointers

Thank you!
Luca

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