From: Sven Eckelmann <sven@narfation.org>
To: b.a.t.m.a.n@lists.open-mesh.org
Cc: Sven Eckelmann <sven@narfation.org>, Felix Kaechele <felix@kaechele.ca>
Subject: [PATCH] batman-adv: Don't skb_split skbuffs with frag_list
Date: Sat, 16 Apr 2022 14:24:34 +0200 [thread overview]
Message-ID: <20220416122434.33061-1-sven@narfation.org> (raw)
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 then 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@kaechele.ca>
Fixes: 9de347143505 ("batman-adv: layer2 unicast packet fragmentation")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
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 0899a729..c120c7c6 100644
--- a/net/batman-adv/fragmentation.c
+++ b/net/batman-adv/fragmentation.c
@@ -475,6 +475,17 @@ 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;
--
2.30.2
next reply other threads:[~2022-04-16 12:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-16 12:24 Sven Eckelmann [this message]
2022-04-16 14:01 ` [PATCH] batman-adv: Don't skb_split skbuffs with frag_list Felix Kaechele
2022-04-16 14:21 ` Andrew Lunn
2022-04-16 17:17 ` Sven Eckelmann
2022-04-16 17:26 ` Andrew Lunn
[not found] ` <165011769041.26690.10778801125078465694@diktynna.open-mesh.org>
2022-04-17 16:07 ` Felix Kaechele
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