Commit c301f098 authored by Dan Carpenter's avatar Dan Carpenter Committed by Pablo Neira Ayuso
Browse files

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



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 caf3ef74 ("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: default avatarDan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent a44af08e

include/net/netfilter/nf_tables.h

+2 −2
Original line number Diff line number Diff line
@@ -178,9 +178,9 @@ static inline __be32 nft_reg_load_be32(const u32 *sreg) 
	return *(__force __be32 *)sreg;

}



static inline void nft_reg_store64(u32 *dreg, u64 val)

static inline void nft_reg_store64(u64 *dreg, u64 val)

{

	put_unaligned(val, (u64 *)dreg);

	put_unaligned(val, dreg);

}



static inline u64 nft_reg_load64(const u32 *sreg)

net/netfilter/nft_byteorder.c

+3 −2
Original line number Diff line number Diff line
@@ -38,13 +38,14 @@ 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 = nft_reg_load64(&src[i]);

				nft_reg_store64(&dst[i],

				nft_reg_store64(&dst64[i],

						be64_to_cpu((__force __be64)src64));

			}

			break;
@@ -52,7 +53,7 @@ void nft_byteorder_eval(const struct nft_expr *expr, 
			for (i = 0; i < priv->len / 8; i++) {

				src64 = (__force __u64)

					cpu_to_be64(nft_reg_load64(&src[i]));

				nft_reg_store64(&dst[i], src64);

				nft_reg_store64(&dst64[i], src64);

			}

			break;

		}

net/netfilter/nft_meta.c

+1 −1
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ nft_meta_get_eval_time(enum nft_meta_keys key, 
{

	switch (key) {

	case NFT_META_TIME_NS:

		nft_reg_store64(dest, ktime_get_real_ns());

		nft_reg_store64((u64 *)dest, ktime_get_real_ns());

		break;

	case NFT_META_TIME_DAY:

		nft_reg_store8(dest, nft_meta_weekday());