netfilter: nft_exthdr: Fix for unsafe packet data read

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While iterating through an SCTP packet's chunks, skb_header_pointer() is
called for the minimum expected chunk header size. If (that part of) the
skbuff is non-linear, the following memcpy() may read data past
temporary buffer '_sch'. Use skb_copy_bits() instead which does the
right thing in this situation.

Fixes: 133dc203d7 ("netfilter: nft_exthdr: Support SCTP chunks")
Suggested-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Phil Sutter <phil@nwl.cc>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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Phil Sutter 2021-06-08 11:40:57 +02:00 • committed by Pablo Neira Ayuso

parent e2cf17d377

commit cf6b5ffdce

1 changed files with 3 additions and 1 deletions

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net/netfilter/nft_exthdr.c

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