Revise sequential access in resampling operations #4643
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The fuzzer bug reported https://github.com/libvips/libvips/actions/runs/17152025286/job/48660246466 is quite interesting. It seems that the removal of the seq hint in libvips/libvips/iofuncs/buffer.c Lines 484 to 494 in 9cc54a0 At first, I thought this would be an easy fix (see commit baf91e4), but it turned out to confuse FFTW's SIMD alignment checks, which I worked around in commit f570895. Unfortunately, crashes still occur in certain cases, for example: $ vips black crash1.pgm 1 70
$ ./build/fuzz/thumbnail_fuzzer -rss_limit_mb=2560 -timeout=25 -runs=100 ./crash1.pgm < /dev/nulli.e. we can't guarantee that I dropped the previous mentioned commits in favor of commit 3037cb3, but still need to verify whether that is safe on all targets. |
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Note to self: the Details--- a/libvips/iofuncs/object.c
+++ b/libvips/iofuncs/object.c
@@ -1883,11 +1883,7 @@ vips_object_set_argument_from_string(VipsObject *object,
if (VIPS_IS_OPERATION(object))
flags = vips_operation_get_flags(VIPS_OPERATION(object));
- if (flags &
- (VIPS_OPERATION_SEQUENTIAL_UNBUFFERED | VIPS_OPERATION_SEQUENTIAL))
- access = VIPS_ACCESS_SEQUENTIAL;
- else
- access = VIPS_ACCESS_RANDOM;
+ access = VIPS_ACCESS_SEQUENTIAL;
if (!value) {
vips_object_no_value(object, name);
@@ -1962,11 +1958,7 @@ vips_object_set_argument_from_string(VipsObject *object,
flags = vips_operation_get_flags(
VIPS_OPERATION(object));
- if (flags &
- (VIPS_OPERATION_SEQUENTIAL_UNBUFFERED | VIPS_OPERATION_SEQUENTIAL))
- access = VIPS_ACCESS_SEQUENTIAL;
- else
- access = VIPS_ACCESS_RANDOM;
+ access = VIPS_ACCESS_SEQUENTIAL;
if (!(array_image =
vips_array_image_new_from_string(value, access)))Still causes out-of-order read on the CLI: $ vips black x.jpg 10000 10000
$ VIPS_STALL=1 vips reducev x.jpg x.v 2 --vips-concurrency 6
vips_worker_work_unit: stall done, releasing y = 0 ...
(vips:15934): VIPS-WARNING **: 11:46:24.438: error in tile 0 x 248
(vips:15934): VIPS-WARNING **: 11:46:24.438: error in tile 0 x 256
(vips:15934): VIPS-WARNING **: 11:46:24.438: error in tile 0 x 264
(vips:15934): VIPS-WARNING **: 11:46:24.438: error in tile 0 x 272
(vips:15934): VIPS-WARNING **: 11:46:24.438: error in tile 0 x 280
(vips:15934): VIPS-WARNING **: 11:46:24.438: error in tile 0 x 288
vips_worker_work_unit: stall done, releasing y = 0 ...
VipsJpeg: out of order read at line 776 |
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More testing is needed, so opened as a draft.
Resolves: #2757.