Zero hdrtoken heap to fix use-of-uninitialized-value#13172
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The hdrtoken heap allocated in hdrtoken_init() leaves padding bytes between each token's null terminator and the next prefix slot uninitialized, since ink_strlcpy only writes strlen+1 bytes but heap_ptr advances by sstr_len (rounded up to sizeof(HdrTokenHeapPrefix)). Switch to ats_calloc so the padding bytes are zeroed. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Pull request overview
This PR fixes an OSS-Fuzz “use-of-uninitialized-value” report in ATS header token initialization by ensuring the heap used to store token strings has its padding bytes zero-initialized.
Changes:
- Replace
ats_malloc(heap_size)withats_calloc(1, heap_size)for_hdrtoken_strs_heap_fallocation inhdrtoken_init(), zeroing padding bytes between strings.
JosiahWI
approved these changes
May 18, 2026
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The hdrtoken heap allocated in hdrtoken_init() leaves padding bytes between each token's null terminator and the next prefix slot uninitialized, since ink_strlcpy only writes strlen+1 bytes but heap_ptr advances by sstr_len (rounded up to sizeof(HdrTokenHeapPrefix)). Switch to ats_calloc so the padding bytes are zeroed.
This fixes the reported fuzzing issues
https://oss-fuzz.com/testcase-detail/4669620266270720