From: Sven Eckelmann <sven@xxxxxxxxxxxxx>
[ Upstream commit a063f2fba3fa633a599253b62561051ac185fa99 ]
The receiving interface might have used GRO to receive more fragments than
MAX_SKB_FRAGS fragments. In this case, these will not be stored in
skb_shinfo(skb)->frags but merged into the frag list.
batman-adv relies on the function skb_split to split packets up into
multiple smaller packets which are not larger than the MTU on the outgoing
interface. But this function cannot handle frag_list entries and is only
operating on skb_shinfo(skb)->frags. If it is still trying to split such an
skb and xmit'ing it on an interface without support for NETIF_F_FRAGLIST,
then validate_xmit_skb() will try to linearize it. But this fails due to
inconsistent information. And __pskb_pull_tail will trigger a BUG_ON after
skb_copy_bits() returns an error.
In case of entries in frag_list, just linearize the skb before operating on
it with skb_split().
Reported-by: Felix Kaechele <felix@xxxxxxxxxxx>
Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Tested-by: Felix Kaechele <felix@xxxxxxxxxxx>
Signed-off-by: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/batman-adv/fragmentation.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c
index 4842436c55f3..a50c87329bc5 100644
--- a/net/batman-adv/fragmentation.c
+++ b/net/batman-adv/fragmentation.c
@@ -489,6 +489,17 @@ int batadv_frag_send_packet(struct sk_buff *skb,
goto free_skb;
}
+ /* GRO might have added fragments to the fragment list instead of
+ * frags[]. But this is not handled by skb_split and must be
+ * linearized to avoid incorrect length information after all
+ * batman-adv fragments were created and submitted to the
+ * hard-interface
+ */
+ if (skb_has_frag_list(skb) && __skb_linearize(skb)) {
+ ret = -ENOMEM;
+ goto free_skb;
+ }
+
/* Create one header to be copied to all fragments */
frag_header.packet_type = BATADV_UNICAST_FRAG;
frag_header.version = BATADV_COMPAT_VERSION;
--
2.35.1
