[PATCH net] ipv4: Don't override return code from ip_route_input_noref()

After ip_route_input() calls ip_route_input_noref(), another
check on skb_dst() is done, but if this fails, we shouldn't
override the return code from ip_route_input_noref(), as it
could have been more specific (i.e. -EHOSTUNREACH).

This also saves one call to skb_dst_force_safe() and one to
skb_dst() in case the ip_route_input_noref() check fails.

Reported-by: Sabrina Dubroca <redacted>
Fixes: ad65a2f05695 ("ipv4: call dst_hold_safe() properly")
Signed-off-by: Stefano Brivio <redacted>
---
 include/net/route.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/net/route.h b/include/net/route.h
index cb0a76d9dde1..1b09a9368c68 100644
--- a/include/net/route.h
+++ b/include/net/route.h

@@ -189,10 +189,11 @@ static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
 
 	rcu_read_lock();
 	err = ip_route_input_noref(skb, dst, src, tos, devin);
-	if (!err)
+	if (!err) {
 		skb_dst_force_safe(skb);
-	if (!skb_dst(skb))
-		err = -EINVAL;
+		if (!skb_dst(skb))
+			err = -EINVAL;
+	}
 	rcu_read_unlock();
 
 	return err;

-- 
2.9.4

After ip_route_input() calls ip_route_input_noref(), another
check on skb_dst() is done, but if this fails, we shouldn't
override the return code from ip_route_input_noref(), as it
could have been more specific (i.e. -EHOSTUNREACH).

This also saves one call to skb_dst_force_safe() and one to
skb_dst() in case the ip_route_input_noref() check fails.

Reported-by: Sabrina Dubroca <redacted>
Fixes: ad65a2f05695 ("ipv4: call dst_hold_safe() properly")
Signed-off-by: Stefano Brivio <redacted>

Acked-by: Wei Wang <redacted>


On Thu, Aug 31, 2017 at 9:11 AM, Stefano Brivio [off-list ref] wrote:

2017-08-31, 18:11:41 +0200, Stefano Brivio wrote:

After ip_route_input() calls ip_route_input_noref(), another
check on skb_dst() is done, but if this fails, we shouldn't
override the return code from ip_route_input_noref(), as it
could have been more specific (i.e. -EHOSTUNREACH).

This also saves one call to skb_dst_force_safe() and one to
skb_dst() in case the ip_route_input_noref() check fails.

Reported-by: Sabrina Dubroca <redacted>
Fixes: ad65a2f05695 ("ipv4: call dst_hold_safe() properly")

That should be instead:

Fixes: 9df16efadd2a ("ipv4: call dst_hold_safe() properly")

Acked-by: Sabrina Dubroca <sd@queasysnail.net>

-- 
Sabrina

From: Sabrina Dubroca <sd@queasysnail.net>
Date: Fri, 1 Sep 2017 01:45:06 +0200

2017-08-31, 18:11:41 +0200, Stefano Brivio wrote:

quoted

After ip_route_input() calls ip_route_input_noref(), another
check on skb_dst() is done, but if this fails, we shouldn't
override the return code from ip_route_input_noref(), as it
could have been more specific (i.e. -EHOSTUNREACH).

This also saves one call to skb_dst_force_safe() and one to
skb_dst() in case the ip_route_input_noref() check fails.

Reported-by: Sabrina Dubroca <redacted>
Fixes: ad65a2f05695 ("ipv4: call dst_hold_safe() properly")

That should be instead:

Fixes: 9df16efadd2a ("ipv4: call dst_hold_safe() properly")

Acked-by: Sabrina Dubroca <sd@queasysnail.net>

Applied with fixed Fixes: tag, thanks.