#9452: freeGroup: block size is zero ----------------------------------+---------------------------------------- Reporter: scott.sadler | Owner: simonmar Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.8.3 Keywords: | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: Runtime crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: ----------------------------------+---------------------------------------- I'm trying to extract pixels from OpenGL and read them into a ForeignPointer, but getting a segfault while doing a peek operation. The fault is on line 240 in `peekArray`. It crashes in different ways depending on the arguments to `readPixelArray`. with `readPixelArray 0 0 100 100`: {{{ (lldb) run Process 26467 launched: '/Users/scott/Code/grids/dist/build/grids/grids' (x86_64) 0x00000001015b3010 Process 26467 stopped * thread #1: tid = 0x23d3cc, 0x0000000100621ead grids`evacuate + 157, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0xfffffffffffffff8) frame #0: 0x0000000100621ead grids`evacuate + 157 grids`evacuate + 157: -> 0x100621ead: movl -0x8(%r12), %esi 0x100621eb2: leal -0x1(%rsi), %ecx 0x100621eb5: cmpl $0x3b, %ecx 0x100621eb8: ja 0x1006222a9 ; evacuate + 1177 }}} with `readPixelArray 0 0 200 200`: (lldb) run Process 26647 launched: '/Users/scott/Code/grids/dist/build/grids/grids' (x86_64) 0x00000001095d8010 grids: internal error: freeGroup: block size is zero (GHC version 7.8.3 for x86_64_apple_darwin) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Process 26647 stopped * thread #1: tid = 0x23f4d4, 0x00007fff8b2cc866 libsystem_kernel.dylib`__pthread_kill + 10, queue = 'com.apple.main- thread', stop reason = signal SIGABRT frame #0: 0x00007fff8b2cc866 libsystem_kernel.dylib`__pthread_kill + 10 libsystem_kernel.dylib`__pthread_kill + 10: -> 0x7fff8b2cc866: jae 0x7fff8b2cc870 ; __pthread_kill + 20 0x7fff8b2cc868: movq %rax, %rdi 0x7fff8b2cc86b: jmpq 0x7fff8b2c9175 ; cerror_nocancel 0x7fff8b2cc870: ret The "freeGroup: block size is zero" message appears in the second output. I'm stumped trying to debug this one. I didn't get as far as trying to go backwards in time debugging it because of lack of familiarity with lldb. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9452 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler