Re: [PATCH net v2 2/2] ipmr: fix error path when ipmr_new_table fails

[David Miller <davem@davemloft.net>]

From: Sabrina Dubroca <sd@queasysnail.net>
Date: Tue,  5 Jun 2018 15:02:00 +0200

> commit 0bbbf0e7d0e7 ("ipmr, ip6mr: Unite creation of new mr_table")
> refactored ipmr_new_table, so that it now returns NULL when
> mr_table_alloc fails. Unfortunately, all callers of ipmr_new_table
> expect an ERR_PTR.
> 
> This can result in NULL deref, for example when ipmr_rules_exit calls
> ipmr_free_table with NULL net->ipv4.mrt in the
> !CONFIG_IP_MROUTE_MULTIPLE_TABLES version.
> 
> This patch makes mr_table_alloc return errors, and changes
> ip6mr_new_table and its callers to return/expect error pointers as
> well. It also removes the version of mr_table_alloc defined under
> !CONFIG_IP_MROUTE_COMMON, since it is never used.
> 
> Fixes: 0bbbf0e7d0e7 ("ipmr, ip6mr: Unite creation of new mr_table")
> Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
> ---
> v2: - fixed brainfart that shadowed mrt variable in ip6_mroute_setsockopt
>     - rebased on top of ip6_mroute_setsockopt fix

Applied and queued up for -stable.