Commit fca41e5b authored Nov 03, 2023 by Dan Carpenter Committed by Greg Kroah-Hartman Feb 23, 2024

netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval()



commit c301f0981fdd3fd1ffac6836b423c4d7a8e0eb63 upstream.

The problem is in nft_byteorder_eval() where we are iterating through a
loop and writing to dst[0], dst[1], dst[2] and so on...  On each
iteration we are writing 8 bytes.  But dst[] is an array of u32 so each
element only has space for 4 bytes.  That means that every iteration
overwrites part of the previous element.

I spotted this bug while reviewing commit caf3ef7468f7 ("netfilter:
nf_tables: prevent OOB access in nft_byteorder_eval") which is a related
issue.  I think that the reason we have not detected this bug in testing
is that most of time we only write one element.

Fixes: ce1e7989 ("netfilter: nft_byteorder: provide 64bit le/be conversion")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
[Ajay: Modified to apply on v4.19.y]
Signed-off-by: Ajay Kaher <ajay.kaher@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent f8f51085

net/netfilter/nft_byteorder.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -41,19 +41,20 @@ static void nft_byteorder_eval(const struct nft_expr *expr,

		switch (priv->size) {
		case 8: {
		u64 dst64 = (void )dst;
		u64 src64;

		switch (priv->op) {
		case NFT_BYTEORDER_NTOH:
		for (i = 0; i < priv->len / 8; i++) {
		src64 = get_unaligned((u64 *)&src[i]);
		put_unaligned_be64(src64, &dst[i]);
		put_unaligned_be64(src64, &dst64[i]);
		}
		break;
		case NFT_BYTEORDER_HTON:
		for (i = 0; i < priv->len / 8; i++) {
		src64 = get_unaligned_be64(&src[i]);
		put_unaligned(src64, (u64 *)&dst[i]);
		put_unaligned(src64, &dst64[i]);
		}
		break;
		}