zebra: fix neighbor table name length

[kunkku]

Toggling user-space neighbor discovery for IPv6 did not work because the table name was not fully copied to the Netlink message.

[donaldsharp]

can I get an example of what is actually broken here? I'm a bit cornfused.

[kunkku]

The issue here is that the length of the NDTA_NAME attribute is hard-coded to 10, whereas the correct length of ndisc_cache is 11. This results in the trailing e not being copied to the Netlink message. Consequently, nhrpd will not get notified when the kernel attempts to perform neighbor solicitation on the target interface.

The correct length of arp_cache is 9, but as the constant string is null-terminated and the field in the Netlink message is anyway padded with null bytes to the length of 12, this error has no effect on IPv4.

[eqvinox]

can I get an example of what is actually broken here? I'm a bit cornfused.

We're copying the string "ndisc_cache" with a length of 10. That string is 11 characters :laughing:

[ton31337]

@Mergifyio backport stable/10.4 stable/10.3 stable/10.2

[mergify[bot]]

backport stable/10.4 stable/10.3 stable/10.2

✅ Backports have been created

• #19734 zebra: fix neighbor table name length (backport #18872) has been created for branch stable/10.4
• #19735 zebra: fix neighbor table name length (backport #18872) has been created for branch stable/10.3
• #19736 zebra: fix neighbor table name length (backport #18872) has been created for branch stable/10.2

[mjstapp]

@Mergifyio backport dev/10.5

[mergify[bot]]

backport dev/10.5

✅ Backports have been created

• #19737 zebra: fix neighbor table name length (backport #18872) has been created for branch dev/10.5

[mjstapp]

@eqvinox @ton31337 any remaining questions? can you approve so we can merge this?

[ton31337]

nothing from my side

[mjstapp]

nothing from my side

how about ... approving it then? I think the rest of us don't want to merge when it appears you still have questions?

[donaldsharp]

@margifyio backport dev/10.5