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netutils/dhcp6c: validate stored option lengths - #3898
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The DHCPv6 client result path trusted previously stored IA_NA, IA_PD, and DNS option data before copying fixed-size IPv6 addresses into the reported client state. A malicious DHCPv6 reply could provide truncated options, or omit DNS data entirely, and later trigger an out-of-bounds read or NULL pointer dereference while building the callback result. Check that stored IA address and prefix options have enough payload for the fixed fields being read, and only copy DNS data when a complete IPv6 address is present. Skip malformed stored options instead of consuming short buffers. Signed-off-by: chao an <anchao.archer@bytedance.com>
xiaoxiang781216
approved these changes
Oct 22, 2026
acassis
approved these changes
Oct 23, 2026
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Summary
Harden DHCPv6 client result parsing against malformed options from a malicious DHCPv6 server.
The result path trusted stored IA_NA, IA_PD, and DNS option data before copying fixed-size IPv6 addresses into the reported client state. A truncated IA option or missing/short DNS option could trigger an out-of-bounds read or NULL pointer dereference.
Changes
Testing
sim/pktradio