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: 133dc203d77df ("netfilter: nft_exthdr: Support SCTP chunks")
Suggested-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Phil Sutter <phil@xxxxxx>
---
Changes since v1:
- skb_copy_bits() call error handling added
---
net/netfilter/nft_exthdr.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index 1b0579cb62d08..7f705b5c09de8 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -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));
--
2.31.1
