Patch "fib_trie: Correct /proc/net/route off by one error" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

fib_trie: Correct /proc/net/route off by one error

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
fib_trie-correct-proc-net-route-off-by-one-error.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Alexander Duyck <[email protected]>
Date: Fri, 4 Nov 2016 15:11:57 -0400
Subject: fib_trie: Correct /proc/net/route off by one error

From: Alexander Duyck <[email protected]>

[ Upstream commit fd0285a39b1cb496f60210a9a00ad33a815603e7 ]

The display of /proc/net/route has had a couple issues due to the fact that when I originally rewrote most of fib_trie I made it so that the iterator was tracking the next value to use instead of the current.

In addition it had an off by 1 error where I was tracking the first piece of data as position 0, even though in reality that belonged to the SEQ_START_TOKEN.

This patch updates the code so the iterator tracks the last reported position and key instead of the next expected position and key. In addition it shifts things so that all of the leaves start at 1 instead of trying to report leaves starting with offset 0 as being valid. With these two issues addressed this should resolve any off by one errors that were present in the display of /proc/net/route.

---
 net/ipv4/fib_trie.c |   21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

@@ -2455,22 +2455,19 @@ static struct key_vector *fib_route_get_
 	struct key_vector *l, **tp = &iter->tnode;
 	t_key key;
 
-	/* use cache location of next-to-find key */
+	/* use cached location of previously found key */
 	if (iter->pos > 0 && pos >= iter->pos) {
-		pos -= iter->pos;
 		key = iter->key;
 	} else {
-		iter->pos = 0;
+		iter->pos = 1;
 		key = 0;
 	}
 
-	while ((l = leaf_walk_rcu(tp, key)) != NULL) {
+	pos -= iter->pos;
+
+	while ((l = leaf_walk_rcu(tp, key)) && (pos-- > 0)) {
 		key = l->key + 1;
 		iter->pos++;
-
-		if (--pos <= 0)
-			break;
-
 		l = NULL;
 
 		/* handle unlikely case of a key wrap */

@@ -2479,7 +2476,7 @@ static struct key_vector *fib_route_get_
 	}
 
 	if (l)
-		iter->key = key;	/* remember it */
+		iter->key = l->key;	/* remember it */
 	else
 		iter->pos = 0;		/* forget it */
 

@@ -2507,7 +2504,7 @@ static void *fib_route_seq_start(struct
 		return fib_route_get_idx(iter, *pos);
 
 	iter->pos = 0;
-	iter->key = 0;
+	iter->key = KEY_MAX;
 
 	return SEQ_START_TOKEN;
 }

@@ -2516,7 +2513,7 @@ static void *fib_route_seq_next(struct s
 {
 	struct fib_route_iter *iter = seq->private;
 	struct key_vector *l = NULL;
-	t_key key = iter->key;
+	t_key key = iter->key + 1;
 
 	++*pos;
 

@@ -2525,7 +2522,7 @@ static void *fib_route_seq_next(struct s
 		l = leaf_walk_rcu(&iter->tnode, key);
 
 	if (l) {
-		iter->key = l->key + 1;
+		iter->key = l->key;
 		iter->pos++;
 	} else {
 		iter->pos = 0;

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/net-__skb_flow_dissect-must-cap-its-return-value.patch queue-4.8/fib_trie-correct-proc-net-route-off-by-one-error.patch