Bug#681056: mdadm: segfault with "--grow --continue"

[Sebastian Hegler]

Package: mdadm
Version: 3.2.5-1
Severity: normal

Dear Maintainer,

Answering questions as per Debian suggestions:
* What led up to the situation?
Growing an MD RAID-6 array (md127), having to shut down the host.

* What exactly did you do (or not do) that was effective (or ineffective)?
Assemble the array, notice that grow operation does not continue. Read manual, notice there is an option like "--grow --continue ". Use this on the array.

* What was the outcome of this action?
mdadm segfaults.

* What outcome did you expect instead?
See the RAID array continue to grow.


I dl'ed mdadm-3.2.5 vanilla, and mdadm git. Both present the same behavior. Compiling and running in gdb yields:

root at kuiper:~/mdadm-3.2.5# gdb ./mdadm 
[SNIP]
Reading symbols from /root/mdadm-3.2.5/mdadm...done.
(gdb) set args --grow --continue /dev/md127 
(gdb) run 
Starting program: /root/mdadm-3.2.5/mdadm --grow --continue /dev/md127 

Program received signal SIGSEGV, Segmentation fault.
Grow_continue_command (devname=0x7fffffffe8cc "/dev/md127", fd=7, backup_file=0x0, verbose=0) at Grow.c:4118
4118		if (verify_reshape_position(content,
(gdb) bt
#0  Grow_continue_command (devname=0x7fffffffe8cc "/dev/md127", fd=7, backup_file=0x0, verbose=0) at Grow.c:4118
#1  0x0000000000407ac2 in main (argc=4, argv=0x7fffffffe678) at mdadm.c:1701

root at kuiper:~/mdadm.git# gdb ./mdadm 
[SNIP]
Reading symbols from /root/mdadm.git/mdadm...done.
(gdb) set args --grow --continue /dev/md127 
(gdb) run 
Starting program: /root/mdadm.git/mdadm --grow --continue /dev/md127 

Program received signal SIGSEGV, Segmentation fault.
Grow_continue_command (devname=0x7fffffffe8d0 "/dev/md127", fd=7, backup_file=0x0, verbose=0) at Grow.c:4086
4086		if (verify_reshape_position(content,
(gdb) bt
#0  Grow_continue_command (devname=0x7fffffffe8d0 "/dev/md127", fd=7, backup_file=0x0, verbose=0) at Grow.c:4086
#1  0x0000000000406c39 in main (argc=4, argv=0x7fffffffe678) at mdadm.c:1447