ipv4: Handle attempt to delete multipath route when fib_info contains an nh reference

stable inclusion
from stable-v5.10.158
commit 0b5394229ebae09afc07aabccb5ffd705ffd250e
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7NTXH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0b5394229ebae09afc07aabccb5ffd705ffd250e

--------------------------------

[ Upstream commit 61b91eb3 ]

Gwangun Jung reported a slab-out-of-bounds access in fib_nh_match:
    fib_nh_match+0xf98/0x1130 linux-6.0-rc7/net/ipv4/fib_semantics.c:961
    fib_table_delete+0x5f3/0xa40 linux-6.0-rc7/net/ipv4/fib_trie.c:1753
    inet_rtm_delroute+0x2b3/0x380 linux-6.0-rc7/net/ipv4/fib_frontend.c:874

Separate nexthop objects are mutually exclusive with the legacy
multipath spec. Fix fib_nh_match to return if the config for the
to be deleted route contains a multipath spec while the fib_info
is using a nexthop object.

Fixes: 493ced1a ("ipv4: Allow routes to use nexthop objects")
Fixes: 6bf92d70 ("net: ipv4: fix route with nexthop object delete warning")
Reported-by: NGwangun Jung <exsociety@gmail.com>
Signed-off-by: NDavid Ahern <dsahern@kernel.org>
Reviewed-by: NIdo Schimmel <idosch@nvidia.com>
Tested-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Stable-dep-of: d5082d38 ("ipv4: Fix route deletion when nexthop info is not specified")
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nsanglipeng <sanglipeng1@jd.com>

tools/testing/selftests/net/fib_nexthops.sh

@@ -945,6 +945,11 @@ ipv4_fcnal()
 	log_test $rc 0 "Delete nexthop route warning"
 	run_cmd "$IP route delete 172.16.101.1/32 nhid 12"
 	run_cmd "$IP nexthop del id 12"
+
+	run_cmd "$IP nexthop add id 21 via 172.16.1.6 dev veth1"
+	run_cmd "$IP ro add 172.16.101.0/24 nhid 21"
+	run_cmd "$IP ro del 172.16.101.0/24 nexthop via 172.16.1.7 dev veth1 nexthop via 172.16.1.8 dev veth1"
+	log_test $? 2 "Delete multipath route with only nh id based entry"
 }
 
 ipv4_grp_fcnal()