[PATCH AUTOSEL 6.1 12/26] net/ipv4: return the real errno instead of -EINVAL

[Sasha Levin]

From: xu xin <xu.xin16@xxxxxxxxxx>

[ Upstream commit c67180efc507e04a87f22aa68bd7dd832db006b7 ]

For now, No matter what error pointer ip_neigh_for_gw() returns,
ip_finish_output2() always return -EINVAL, which may mislead the upper
users.

For exemple, an application uses sendto to send an UDP packet, but when the
neighbor table overflows, sendto() will get a value of -EINVAL, and it will
cause users to waste a lot of time checking parameters for errors.

Return the real errno instead of -EINVAL.

Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>
Reviewed-by: Yang Yang <yang.yang29@xxxxxxxxxx>
Cc: Si Hao <si.hao@xxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230807015408.248237-1-xu.xin16@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/ipv4/ip_output.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index acfe58d2f1dd7..831c627e03ff8 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -234,7 +234,7 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
 	net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
 			    __func__);
 	kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
-	return -EINVAL;
+	return PTR_ERR(neigh);
 }
 
 static int ip_finish_output_gso(struct net *net, struct sock *sk,
-- 
2.40.1