Re: [bug-gawk] incorrect checksum for freed object ... Abort trap: 6 ... fatal error: internal error: segfault

[Hermann Peifer]

On 2015-03-11 20:56, Hermann Peifer wrote:
> Thanks for the fix: all errors are gone, after applying the patch...

I am afraid that I have to correct myself: applying the patch only made 
the error occur less often than before.

Below my effort to a) isolate the issue and b) make it occur more often. 
The error now happens in around 1 out of 10 cases (using unpatched 
gawk-4.1-stable). I added some lines from the crash logs, of which I 
have plenty now.

Hermann

$ uname -v
Darwin Kernel Version 14.1.0: Thu Feb 26 19:26:47 PST 2015; 
root:xnu-2782.10.73~1/RELEASE_X86_64

$ ./gawk -V | head -1
GNU Awk 4.1.1c, API: 1.1 (GNU MPFR 3.1.2-p10, GNU MP 6.0.0)

$ ./gawk -o -M 'BEGIN{v=0x0100000000000000000000000000000000}'
gawk(81029,0x7fff73a62300) malloc: *** error for object 0x7fb991407428: 
incorrect checksum for freed object - object was probably modified after 
being freed.
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6

$ ./gawk -o -M 'BEGIN{print 0x0100000000000000000000000000000000}'
340282366920938463463374607431768211456
gawk(81255,0x7fff73a62300) malloc: *** error for object 0x7fda13c072f8: 
incorrect checksum for freed object - object was probably modified after 
being freed.
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6

$ ./gawk -o -M 'BEGIN{print 0x0100000000000000000000000000000000}'
340282366920938463463374607431768211456
gawk: cmd. line:1: fatal error: internal error: segfault
Abort trap: 6


# From the Mac OS X crash logs

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread$
0   libsystem_kernel.dylib  __pthread_kill + 10
1   libsystem_c.dylib       abort + 129
2   libsystem_malloc.dylib  szone_error + 625
3   libsystem_malloc.dylib  tiny_malloc_from_free_list + 1358
4   libsystem_malloc.dylib  szone_malloc_should_clear + 317
5   libsystem_malloc.dylib  malloc_zone_malloc + 71
6   libsystem_malloc.dylib  malloc + 42
7   gawk                    pp_list + 296 (.awk.h:1780)
8   gawk                    pprint + 5335 (profile.c:550)
9   gawk                    pprint + 10893 (profile.c:127)
10  gawk                    dump_prog + 224 (profile.c:984)
11  gawk                    main + 5807 (main.c:509)
12  libdyld.dylib           start + 1

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib  __pthread_kill + 10
1   libsystem_c.dylib       abort + 129
2   libsystem_malloc.dylib  szone_error + 625
3   libsystem_malloc.dylib  szone_free_definite_size + 3454
4   libmpfr.4.dylib         mpfr_clear + 62
5   gawk                    cleanup_mpfr + 16 (mpfr.c:98)
6   gawk                    main + 5851 (main.c:520)
7   libdyld.dylib           start + 1