There is a NULL Pointer Dereference being triggered by running ./gm identify -ping %file%
The relevant Address Sanitizer output is as follows:
./gm_asan identify -ping crashes/n0
ASAN:DEADLYSIGNAL
=================================================================
==6057==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x0000009a69b5 bp 0x7ffd14723d30 sp 0x7ffd14722b40 T0)
==6057==The signal is caused by a WRITE memory access.
==6057==Hint: address points to the zero page.
#0 0x9a69b4 (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x9a69b4)
#1 0x81d663 (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x81d663)
#2 0x5a6491 (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x5a6491)
#3 0x5a5cbf (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x5a5cbf)
#4 0x53ed6b (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x53ed6b)
#5 0x541cc3 (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x541cc3)
#6 0x579ed2 (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x579ed2)
#7 0x578c28 (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x578c28)
#8 0x7fb45bf863f0 (/lib/x86_64-linux-gnu/libc.so.6+0x203f0)
#9 0x41ce39 (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x41ce39)
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/home/ksg/GraphicsMagick-1.3.26/utilities/gm_asan+0x9a69b4)
==6057==ABORTING
The file causing the crash condition is shared for triage purposes.
This issue is also fixed by Mercurial changeset 15170:fb09ca6dd22c. Thank you for the report.