[3.13.y.z extended stable] Patch "batman-adv: Fix out-of-order fragmentation support" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Tue Sep 2 21:37:03 UTC 2014


This is a note to let you know that I have just added a patch titled

    batman-adv: Fix out-of-order fragmentation support

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.7.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 11e9b8e66a85e479609d0b634a2293220768fc45 Mon Sep 17 00:00:00 2001
From: Sven Eckelmann <sven at narfation.org>
Date: Mon, 26 May 2014 17:21:39 +0200
Subject: batman-adv: Fix out-of-order fragmentation support

[ Upstream commit d9124268d84a836f14a6ead54ff9d8eee4c43be5 ]

batadv_frag_insert_packet was unable to handle out-of-order packets because it
dropped them directly. This is caused by the way the fragmentation lists is
checked for the correct place to insert a fragmentation entry.

The fragmentation code keeps the fragments in lists. The fragmentation entries
are kept in descending order of sequence number. The list is traversed and each
entry is compared with the new fragment. If the current entry has a smaller
sequence number than the new fragment then the new one has to be inserted
before the current entry. This ensures that the list is still in descending
order.

An out-of-order packet with a smaller sequence number than all entries in the
list still has to be added to the end of the list. The used hlist has no
information about the last entry in the list inside hlist_head and thus the
last entry has to be calculated differently. Currently the code assumes that
the iterator variable of hlist_for_each_entry can be used for this purpose
after the hlist_for_each_entry finished. This is obviously wrong because the
iterator variable is always NULL when the list was completely traversed.

Instead the information about the last entry has to be stored in a different
variable.

This problem was introduced in 610bfc6bc99bc83680d190ebc69359a05fc7f605
("batman-adv: Receive fragmented packets and merge").

Signed-off-by: Sven Eckelmann <sven at narfation.org>
Signed-off-by: Marek Lindner <mareklindner at neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio at meshcoding.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/batman-adv/fragmentation.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c
index a674034..8a1d4b54 100644
--- a/net/batman-adv/fragmentation.c
+++ b/net/batman-adv/fragmentation.c
@@ -130,6 +130,7 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
 {
 	struct batadv_frag_table_entry *chain;
 	struct batadv_frag_list_entry *frag_entry_new = NULL, *frag_entry_curr;
+	struct batadv_frag_list_entry *frag_entry_last = NULL;
 	struct batadv_frag_packet *frag_packet;
 	uint8_t bucket;
 	uint16_t seqno, hdr_size = sizeof(struct batadv_frag_packet);
@@ -182,11 +183,14 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
 			ret = true;
 			goto out;
 		}
+
+		/* store current entry because it could be the last in list */
+		frag_entry_last = frag_entry_curr;
 	}

-	/* Reached the end of the list, so insert after 'frag_entry_curr'. */
-	if (likely(frag_entry_curr)) {
-		hlist_add_after(&frag_entry_curr->list, &frag_entry_new->list);
+	/* Reached the end of the list, so insert after 'frag_entry_last'. */
+	if (likely(frag_entry_last)) {
+		hlist_add_after(&frag_entry_last->list, &frag_entry_new->list);
 		chain->size += skb->len - hdr_size;
 		chain->timestamp = jiffies;
 		ret = true;
--
1.9.1





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