ipv6: prevent race between address creation and removal
There's a race in IPv6 automatic addess assignment. The address is created with zero lifetime when it's added to various address lists. Before it gets assigned the correct lifetime, there's a window where a new address may be configured. This causes the semi-initiated address to be deleted in addrconf_verify. This was discovered as a reference leak caused by concurrent run of __ipv6_ifa_notify for both RTM_NEWADDR and RTM_DELADDR with the same address. Fix this by setting the lifetime before the address is added to inet6_addr_lst. A few notes: 1. In addrconf_prefix_rcv, by setting update_lft to zero, the if (update_lft) { ... } condition is no longer executed for newly created addresses. This is okay, as the ifp fields are set in ipv6_add_addr now and ipv6_ifa_notify is called (and has been called) through addrconf_dad_start. 2. The removal of the whole block under ifp->lock in inet6_addr_add is okay, too, as tstamp is initialized to jiffies in ipv6_add_addr. Signed-off-by: NJiri Benc <jbenc@redhat.com> Signed-off-by: NJiri Pirko <jiri@resnulli.us> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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