fsck_ufs dumps core

[Konstantin Belousov]

On Wed, Aug 10, 2016 at 05:29:31PM +0300, Dmitry Sivachenko wrote:
> Hello,
> 
> I am running FreeBSD 10.3-STABLE #0 r299261M
> 
> After unclean reboot I am unable to fsck my UFS filesystem:
> 
> # fsck  /dev/mfid0p1
> ** /dev/mfid0p1
> ** Last Mounted on /opt
> ** Phase 1 - Check Blocks and Sizes
> fsck: /dev/mfid0p1: Segmentation fault
> 
> pid 482 (fsck_ufs), uid 0: exited on signal 11 (core dumped)
> 
> # gdb -c fsck_ufs.482 /sbin/fsck_ufs 
> GNU gdb 6.1.1 [FreeBSD]
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "amd64-marcel-freebsd"...
> Core was generated by `fsck_ufs'.
> Program terminated with signal 11, Segmentation fault.
> Reading symbols from /lib/libufs.so.6...done.
> Loaded symbols for /lib/libufs.so.6
> Reading symbols from /lib/libc.so.7...done.
> Loaded symbols for /lib/libc.so.7
> Reading symbols from /libexec/ld-elf.so.1...done.
> Loaded symbols for /libexec/ld-elf.so.1
> #0  0x0000000000409a8b in pass1 () at /place/WRK/src/sbin/fsck_ffs/pass1.c:83
> 83                              setbmap(i);
> (gdb) bt
> #0  0x0000000000409a8b in pass1 () at /place/WRK/src/sbin/fsck_ffs/pass1.c:83
> #1  0x0000000000409050 in main (argc=<value optimized out>, 
>     argv=<value optimized out>) at /place/WRK/src/sbin/fsck_ffs/main.c:447
> Current language:  auto; currently minimal
> (gdb) 
> 

Try to use alternative superblock (-b switch).  You can get the list of
the possible values for -b by 'newfs -N' invocation, but you have to know
the parameters which were used for formatting.