Libvips: segfault in Python oder libvips während der ungefähren Faltung eines kurzen oder ushort-Bildes

Hallo John,

Ich habe mit der ungefähren Faltung experimentiert, die Sie in #1160 erwähnt haben, und bin auf einen anhaltenden Segfault gestoßen, aber nur beim Falten von ushort-Bildern. Ich kann den Segfault je nach Größe des Bildes entweder in Python oder libvips auslösen, daher nehme ich an, dass dies möglicherweise doppelt kostenlos ist. Hier ist ein Testprogramm mit einigen Experimenten, um zu sehen, wo das Problem auftritt. Darunter befindet sich ein Stack-Trace des Segfault-Speicherorts in libvips.so.42.9.0 (ohne Verwendung eines Debugging-Builds im Moment, also vielleicht nicht so hilfreich).

Ich führe vips vips-8.7.0-Sun Jan 28 17:23:05 UTC 2018 verwende die pyvips-Schnittstelle unter Python Python 2.7.15 :: Anaconda custom (64-bit)

Danke im Voraus.

Hinweis: eigentlich eine .py-Datei:
segfault.txt

# /usr/bin/env python
import pyvips

slab = pyvips.Image.new_from_array([[1]*10]*10, scale=100)  # 10x10 moving average

n = 30000 # also segfaults when n=30000.  See note below.

# The following are all fine
uchar_im = pyvips.Image.black(n, n).cast('uchar')  # just to be sure it's uchar
uchar_im.conv(slab, precision='approximate', layers=1).write_to_file('uchar_conv.v')

float_im = pyvips.Image.black(n, n).cast('float')
float_im.conv(slab, precision='approximate', layers=1).write_to_file('float_conv.v')


# EVERY CONVOLUTION BELOW THIS LINE SEGFAULTS

# if n=1, completes by writing result to file, then segfaults in python:
# *** Error in `python': free(): invalid pointer: 0x00005651d79154c0 ***

# if n=30000, does not complete and segfaults in libvips
# [1049087.739802] worker[599]: segfault at 7f4cd631a000 ip 00007f4ce7f93318 sp 00007f4cd2caea70 error 4 in libvips.so.42.9.0[7f4ce7eb6000+1f5000]

ushort_im = pyvips.Image.black(n, n).cast('ushort')
ushort_im.conv(slab.cast('ushort'), precision='approximate', layers=1).write_to_file('ushort_conv.v')  # segfault happens here

ushort_im = pyvips.Image.black(n, n).cast('ushort')
ushort_im.conv(slab, precision='approximate', layers=1).write_to_file('ushort_conv.v')  # segfault would also happen here

short_im = pyvips.Image.black(n, n).cast('short')
short_im.conv(slab, precision='approximate', layers=1).write_to_file('short_conv.v')  # segfault would also happen here

Möglicherweise relevanter Stacktrace bei n=30000:

Thread 52 "worker" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffe64d5700 (LWP 4069)]
0x00007ffff4ab4c7d in ?? () from /usr/lib/libvips.so.42
(gdb) up
#1  0x00007ffff4b4e411 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#2  0x00007ffff4b4f0c9 in vips_region_fill () from /usr/lib/libvips.so.42
(gdb) up
#3  0x00007ffff4b50d53 in vips_region_prepare () from /usr/lib/libvips.so.42
(gdb) up
#4  0x00007ffff4ab65b3 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#5  0x00007ffff4b4e411 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#6  0x00007ffff4b4f0c9 in vips_region_fill () from /usr/lib/libvips.so.42
(gdb) up
#7  0x00007ffff4b50d53 in vips_region_prepare () from /usr/lib/libvips.so.42
(gdb) up
#8  0x00007ffff4b40d59 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#9  0x00007ffff4b4e411 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#10 0x00007ffff4b4f0c9 in vips_region_fill () from /usr/lib/libvips.so.42
(gdb) up
#11 0x00007ffff4b50d53 in vips_region_prepare () from /usr/lib/libvips.so.42
(gdb) up
#12 0x00007ffff4b40d59 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#13 0x00007ffff4b4e411 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#14 0x00007ffff4b4f0c9 in vips_region_fill () from /usr/lib/libvips.so.42
(gdb) up
#15 0x00007ffff4b50d53 in vips_region_prepare () from /usr/lib/libvips.so.42
(gdb) up
#16 0x00007ffff4b40d59 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#17 0x00007ffff4b4e411 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#18 0x00007ffff4b4f615 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#19 0x00007ffff4b50f5f in vips_region_prepare_to () from /usr/lib/libvips.so.42
(gdb) up
#20 0x00007ffff4b48228 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#21 0x00007ffff4b5171b in ?? () from /usr/lib/libvips.so.42
(gdb) up
#22 0x00007ffff4b51504 in ?? () from /usr/lib/libvips.so.42
(gdb) up
#23 0x00007ffff44e0a8a in g_thread_proxy (data=0x5555559df720) from /opt/anaconda/lib/libglib-2.0.so.0
(gdb) up
#24 0x00007ffff77e36ba in start_thread (arg=0x7fffe64d5700) at pthread_create.c:333
333 pthread_create.c: No such file or directory.