From fca41e5b687e029f69e3a35a2fa31e2560e538dc Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 3 Nov 2023 09:42:51 +0300 Subject: [PATCH] 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: ce1e7989d989 ("netfilter: nft_byteorder: provide 64bit le/be conversion") Signed-off-by: Dan Carpenter Signed-off-by: Pablo Neira Ayuso [Ajay: Modified to apply on v4.19.y] Signed-off-by: Ajay Kaher Signed-off-by: Greg Kroah-Hartman --- net/netfilter/nft_byteorder.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nft_byteorder.c b/net/netfilter/nft_byteorder.c index dba16126c7eec..8c4ee49a80fb6 100644 --- a/net/netfilter/nft_byteorder.c +++ b/net/netfilter/nft_byteorder.c @@ -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; }