# uname -r
10.1-RELEASE
# mptutil show drives
Segmentation fault (core dumped)
# mptutil show config
Segmentation fault (core dumped)

Download the 10.1-RELEASE source code and compile mptutil with -g; 
Using GDB:
# gdb ./mptutil
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This GDB was configured as "amd64-marcel-freebsd"...
(gdb) run show drives
Starting program: /root/10.1-RELEASE/10.1.0/usr.sbin/mptutil/mptutil show drives

Program received signal SIGSEGV, Segmentation fault.
0x0000000800f0c24c in sbrk () from /lib/libc.so.7
(gdb) bt
#0  0x0000000800f0c24c in sbrk () from /lib/libc.so.7
#1  0x0000000800f0c7af in sbrk () from /lib/libc.so.7
#2  0x0000000800f17df5 in free () from /lib/libc.so.7
#3  0x000000000040253a in mpt_fetch_disks (fd=<value optimized out>, 
    ndisks=0x7fffffffe9bc, disksp=0x7fffffffe9c0) at mpt_cam.c:292
#4  0x0000000000405ce9 in show_drives (ac=<value optimized out>, av=<value optimized out>)
    at mpt_show.c:500
#5  0x000000000040192c in main (ac=2, av=0x7fffffffea98) at mptutil.c:117
(gdb) frame 3
#3  0x000000000040253a in mpt_fetch_disks (fd=<value optimized out>, 
    ndisks=0x7fffffffe9bc, disksp=0x7fffffffe9c0) at mpt_cam.c:292
292			cam_freeccb(ccb);
Current language:  auto; currently minimal
(gdb) l
287			cam_freeccb(ccb);
288			return (error);
289		}
290	
291		if ((ccb->ccb_h.status & CAM_STATUS_MASK) != CAM_REQ_CMP) {
292			cam_freeccb(ccb);
293			return (EIO);
294		}
295		cam_freeccb(ccb);
296	
(gdb) p ccb->ccb_h.status
$1 = 1

Looks ccb was freed at line mpt_cam.c:263 already and reused later.
this is maybe the reason segment fault when ccb is freed again at mpt_cam.c:292.

Comment line 291-295 out, it does not crash. But not the right way to fix.