Reject negative size in mergeDelimitedFrom#28097
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readRawVarint32 returns a negative int for 5-byte varints encoding values >= 2^31. mergeDelimitedFrom passes this directly to LimitedInputStream, which treats negative limits as EOF. This silently produces an empty message and leaves the actual body bytes unconsumed, desynchronizing subsequent parseDelimitedFrom calls on the same stream. Add a negative size check before constructing LimitedInputStream.
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Summary
mergeDelimitedFrompasses the return value ofreadRawVarint32directly toLimitedInputStreamwithout checking for negative values. For 5-byte varints encoding values >= 2^31,readRawVarint32returns a negative int (e.g.,\x80\x80\x80\x80\x08decodes to -2147483648).LimitedInputStreamwith a negative limit immediately returns EOF (if (limit <= 0) return -1), causing the parser to produce a default/empty message and returntrue(success). The actual message body bytes remain unconsumed in the stream, permanently desynchronizing subsequentparseDelimitedFromcalls.Fix
Add
if (size < 0) throw InvalidProtocolBufferException.negativeSize()before constructingLimitedInputStream.Test plan
negativeSizeexception thrown