net/icmpv6/icmpv6_input.c: Dont increase d_pktsize from router advertise#18866
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xiaoxiang781216 merged 1 commit intoMay 12, 2026
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An IPV6 Router advertisement can have an MTU max option. This option should not increase the d_pktsize for a given interface since that max size might have been set based on CONFIG or buffer size. Signed-off-by: daniellizewski <daniellizewski@geotab.com>
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xiaoxiang781216
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Summary
An IPV6 Router advertisement can have an MTU option. This option should not increase the d_pktsize for a given interface since that max size might have been set based on CONFIG or buffer size.
Change the processing code to only allow decreasing MTU
Impact
Testing
Here is an image of captured network data showing an MTU of 1428. This was overriding/increasing my Kconfig set MTU of 1400 for my tun interface set in CONFIG_NET_TUN_PKTSIZE