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KPM: new[]/delete mismatch in vision::Image and leaked imageInfo in kpmDeleteHandle

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Assessment

Difficulty
3/5
Estimated time
Half a day
Newbie friendliness
66/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
cpp
Domain
computer-vision

Research direction

Start with the allocation in vision::Image::alloc (lib/SRC/KPM/FreakMatcher/framework/image.cpp, around line 149) and the destructor around line 118, which the shared_ptr deleter uses. Then read kpmDeleteHandle in lib/SRC/KPM/kpmHandle.cpp (lines 245-246) and kpmSetRefDataSet in lib/SRC/KPM/kpmMatching.cpp (line 243) to see how per-page imageInfo is freed on replacement. Done when an ASan build of webarkit_nft_core_test reports no alloc-dealloc-mismatch or leaks from these sites.

Written by the indexing model from the issue text.

Description

bug C/C++ code

Description

AddressSanitizer runs of the NFT core tests (webarkit/jsartoolkitNFT#683, webarkit_nft_core_test, 49 tests passing) found two pre-existing problems in the vendored KPM code. Neither is in the new core.

1. Allocation/deallocation mismatch in vision::Image

vision::Image::alloc (lib/SRC/KPM/FreakMatcher/framework/image.cpp:149) allocates with new unsigned char[...], and the buffer is owned by a std::shared_ptr<unsigned char> with the default deleter, which calls delete (not delete[]) in vision::Image::~Image (image.cpp:118). ASan aborts on alloc-dealloc-mismatch (operator new [] vs operator delete) in the first KPM test.

Fix: give the shared_ptr an array deleter (std::default_delete<unsigned char[]>()), or use std::shared_ptr<unsigned char[]> where the standard allows.

2. Leaked per-page imageInfo in kpmDeleteHandle

With ASAN_OPTIONS=alloc_dealloc_mismatch=0, LeakSanitizer reports 6732 bytes in 54 allocations. All 40 leak reports are allocated in kpmSetRefDataSet (lib/SRC/KPM/kpmMatching.cpp:243), which allocates each page's imageInfo array. kpmDeleteHandle (kpmHandle.cpp:245-246) frees pageInfo but not the per-page imageInfo; only a later kpmSetRefDataSet frees them when it replaces a set.

Fix: in kpmDeleteHandle, free each pageInfo[i].imageInfo before freeing pageInfo, mirroring what kpmSetRefDataSet does on replacement.

Notes

With these (and the thread_sub.c mutex issue), sanitizer runs exit non-zero even when the code under test is clean, so a sanitizer CI job would need suppressions until they are fixed.

Dominant language
C++
Stars
21
Forks
8
Avg merge
7h 30m
Merged PRs (30d)
25

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