Commit cf6b5ffd authored by Phil Sutter's avatar Phil Sutter Committed by Pablo Neira Ayuso
Browse files

netfilter: nft_exthdr: Fix for unsafe packet data read 



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: 133dc203 ("netfilter: nft_exthdr: Support SCTP chunks")
Suggested-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPhil Sutter <phil@nwl.cc>
Reviewed-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent e2cf17d3

net/netfilter/nft_exthdr.c

+3 −1
Original line number Diff line number Diff line
@@ -327,7 +327,9 @@ static void nft_exthdr_sctp_eval(const struct nft_expr *expr, 
				break;



			dest[priv->len / NFT_REG32_SIZE] = 0;

			memcpy(dest, (char *)sch + priv->offset, priv->len);

			if (skb_copy_bits(pkt->skb, offset + priv->offset,

					  dest, priv->len) < 0)

				break;

			return;

		}

		offset += SCTP_PAD4(ntohs(sch->length));