IPv6: Compute extension header offset in uint32 to avoid overflow.#13702
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agilira wants to merge 1 commit into
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IPv6: Compute extension header offset in uint32 to avoid overflow.#13702agilira wants to merge 1 commit into
agilira wants to merge 1 commit into
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IPv6PayloadIterator advanced nextOffset by (length + 1) * ipv6ExtHdrLenBytesPerUnit. Because length is uint8 and ipv6ExtHdrLenBytesPerUnit is the untyped constant 8, the expression was evaluated in uint8 and wrapped for any Hdr Ext Len >= 31, advancing nextOffset by a too-small amount. nextOffset feeds HeaderOffset() and ParseOffset(), which are used to locate the transport header in the fdbased receive path and to report the ICMP Parameter-Problem pointer. The extension header data itself was already read with correct int math, so this only affects the reported offsets, not memory safety. Compute the increment in uint32. Add a regression test that parses a Destination Options header with Hdr Ext Len = 31 and checks HeaderOffset(). Assisted-by: Claude Code
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IPv6PayloadIterator advanced nextOffset by
(length + 1) * ipv6ExtHdrLenBytesPerUnit. Because length is uint8 and ipv6ExtHdrLenBytesPerUnit is the untyped constant 8, the expression was evaluated in uint8 and wrapped for any Hdr Ext Len >= 31, advancing nextOffset by a too-small amount.
nextOffset feeds HeaderOffset() and ParseOffset(), which are used to locate the transport header in the fdbased receive path and to report the ICMP Parameter-Problem pointer. The extension header data itself was already read with correct int math, so this only affects the reported offsets, not memory safety.
Compute the increment in uint32. Add a regression test that parses a Destination Options header with Hdr Ext Len = 31 and checks HeaderOffset().
Assisted-by: Claude Code