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[C] Bound var data against the remaining buffer so a uint64 length cannot wrap the position - #1178
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slachiewicz wants to merge 1 commit into
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slachiewicz wants to merge 1 commit into
slachiewicz wants to merge 1 commit into
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…nnot wrap the position. Compare data_length with buffer_length - pos rather than passing pos + data_length to set_sbe_position, which wraps for a uint64 length and lets the position move backwards. Do not go back to the addition.
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With a uint64 var data length, the position + length passed to _set_sbe_position() can wrap and pass the bounds check, so get() copies past the buffer and the position moves backwards.
(), get_() and get__as_string_view() now compare the length with buffer_length - position, which cannot wrap, and return 0 or NULL with errno E100.
Part of #969.
Verified: CVarDataUint64LengthTest fails on master (heap-buffer-overflow in get_payload() under ASan) and passes here; sbe-tool checkstyle and test, cppbuild and cppbuild --debug-build --sanitise-build pass.