[PATCH] net: fib_rules: add FRA_GOTO and FRA_L3MDEV to fib_rule_nlmsg_size()

[Linkui Xiao]

From: Linkui Xiao <xiaolinkui@xxxxxxxxxx>

fib_nl_fill_rule() emits FRA_GOTO and FRA_L3MDEV, but
fib_rule_nlmsg_size() reserves room for neither. Its only caller,
notify_rule_change(), allocates the notification skb with that size and
treats a failure as a bug:

	/* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */

A rule that has both a goto target and l3mdev set needs 16 more bytes
than are reserved. nlmsg_new() rounds the allocation up through
SKB_DATA_ALIGN(), so the slack hides the mistake most of the time and
the bug stays latent, but the accounting is wrong and the notification
can still fail with -EMSGSIZE.

Reserve the two missing attributes, keeping the order used by
fib_nl_fill_rule().

Fixes: 0947c9fe56d9 ("[NET] fib_rules: goto rule action")
Fixes: 96c63fa7393d ("net: Add l3mdev rule")
Signed-off-by: Linkui Xiao <xiaolinkui@xxxxxxxxxx>
---
 net/core/fib_rules.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 7df216c17c67..5e84bc740191 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -1133,7 +1133,9 @@ static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
 			 + nla_total_size(4) /* FRA_SUPPRESS_IFGROUP */
 			 + nla_total_size(4) /* FRA_FWMARK */
 			 + nla_total_size(4) /* FRA_FWMASK */
+			 + nla_total_size(4) /* FRA_GOTO */
 			 + nla_total_size_64bit(8) /* FRA_TUN_ID */
+			 + nla_total_size(1) /* FRA_L3MDEV */
 			 + nla_total_size(sizeof(struct fib_kuid_range))
 			 + nla_total_size(1) /* FRA_PROTOCOL */
 			 + nla_total_size(1) /* FRA_IP_PROTO */
-- 
2.25.1