[PATCH 4.20 009/127] ipv6: Fix dump of specific table with strict checking

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

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

From: David Ahern <dsahern@xxxxxxxxx>

[ Upstream commit 73155879b3c1ac3ace35208a54a3a160ec520bef ]

Dump of a specific table with strict checking enabled is looping. The
problem is that the end of the table dump is not marked in the cb. When
dumping a specific table, cb args 0 and 1 are not used (they are the hash
index and entry with an hash table index when dumping all tables). Re-use
args[0] to hold a 'done' flag for the specific table dump.

Fixes: 13e38901d46ca ("net/ipv6: Plumb support for filtering route dumps")
Reported-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
Signed-off-by: David Ahern <dsahern@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/ipv6/ip6_fib.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -627,7 +627,11 @@ static int inet6_dump_fib(struct sk_buff
 			return -ENOENT;
 		}
 
-		res = fib6_dump_table(tb, skb, cb);
+		if (!cb->args[0]) {
+			res = fib6_dump_table(tb, skb, cb);
+			if (!res)
+				cb->args[0] = 1;
+		}
 		goto out;
 	}