[Crash-utility] Crash faults when determining panic task

I have a vmcore generated on RHEL6.1 that newer versions of crash have trouble analyzing (5.1.1-2.el6 seems to work ok). I can provide additional binary files if needed, just let me know what convention best suits the list (ftp, private email attachment, etc.) Crash Version: OS: Result: crash 5.1.8 Debian wheezy faults crash 5.1.7-1.el6 RHEL6.2 Alpha faults crash 5.1.1-2.el6 RHEL6.1 ok Kernel: 2.6.32-131.0.15.el6.exp10.bz16586.x86_64 (2.6.32-131.0.15 + a fix for Red Hat bz-707268) Interesting warnings when starting crash: WARNING: sparsemem: invalid section number: 137438888923 WARNING: sparsemem: invalid section number: 137438888923 First fault, null pointer deference: please wait... (determining panic task) Program received signal SIGSEGV, Segmentation fault. x86_64_get_dumpfile_stack_frame (rsp=0x7fffffffcc58, rip=0x7fffffffcc50, bt_in=0x7fffffffcce0) at x86_64.c:4183 4183 ur_rip = ULONG(user_regs + (gdb) p user_regs $1 = 0x0 Workaround, check that bt->machdep is not NULL: diff -Nupr crash-5.1.8/x86_64.c crash-5.1.8.new/x86_64.c --- crash-5.1.8/x86_64.c 2011-09-16 15:01:12.000000000 -0400 +++ crash-5.1.8.new/x86_64.c 2011-09-28 14:12:45.347188571 -0400 @@ -4178,7 +4178,7 @@ x86_64_get_dumpfile_stack_frame(struct b goto skip_stage; } } - } else if (ELF_NOTES_VALID()) { + } else if (ELF_NOTES_VALID() && bt->machdep) { user_regs = bt->machdep; ur_rip = ULONG(user_regs + OFFSET(user_regs_struct_rip)); Second fault, a curiously large n_descsz in elf note header: please wait... (determining panic task) Program received signal SIGSEGV, Segmentation fault. get_regs_from_note (note=0xd26472 "\b", ip=0x7fffffffc4e0, sp=0x7fffffffc4e8) at netdump.c:2221 2221 *sp = ULONG(user_regs + offset_sp); (gdb) p *(Elf64_Nhdr *)note $1 = {n_namesz = 8, n_descsz = 3438804992, n_type = 8} Workaround, do not attempt reading registers from elf notes (this chunk of code was not present in crash 5.1.1): diff -Nupr crash-5.1.8/netdump.c crash-5.1.8.new/netdump.c --- crash-5.1.8/netdump.c 2011-09-16 15:01:12.000000000 -0400 +++ crash-5.1.8.new/netdump.c 2011-09-28 14:14:43.687183734 -0400 @@ -2286,7 +2286,7 @@ get_netdump_regs_x86_64(struct bt_info * bt->machdep = (void *)user_regs; } - +#if 0 if (ELF_NOTES_VALID() && (bt->flags & BT_DUMPFILE_SEARCH) && DISKDUMP_DUMPFILE() && (note = (Elf64_Nhdr *) @@ -2305,7 +2305,7 @@ get_netdump_regs_x86_64(struct bt_info * bt->machdep = (void *)user_regs; } - +#endif machdep->get_stack_frame(bt, ripp, rspp); } Given the warning messages at the beginning of the process, I'm sure if I'm dealing with a corrupted or incomplete vmcore image. Let me know what additional info could be useful if this seems worth debugging further. Thanks, -- Joe Lawrence