common/bolt12: fix tlv_span() behaviour with empty tlvstream
#8364
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added 2 commits
June 19, 2025 08:18
Changelog-Fixed: When `tlv_span()` receives an empty `tlvsteam`, it sets the value of `startp` to `start` - `tlvstream` = `NULL` - `tlvstream` where `tlvstream` is a pointer. This is undefined behaviour. Add a guard against it by correcting the initial value of `end`.
Add a test that reproduces the UB when the fix is not applied.
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When
tlv_span()receives an emptytlvsteam, it sets the value ofstartptostart-tlvstream=NULL-tlvstream, wheretlvstreamis a pointer.This is undefined behaviour. Add a guard against it by correcting the initial value of
end.Checklist
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CC: @morehouse