| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.17 001/114] batman-adv: Dont skb_split skbuffs with frag_list | Date | Mon, 16 May 2022 21:35:35 +0200 |
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From: Sven Eckelmann <sven@narfation.org>
[ 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@kaechele.ca> Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol") Signed-off-by: Sven Eckelmann <sven@narfation.org> Tested-by: Felix Kaechele <felix@kaechele.ca> Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de> Signed-off-by: Sasha Levin <sashal@kernel.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 0899a729a23f..c120c7c6d25f 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; -- 2.35.1
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