netdev - [PATCH v5.10.y] netfilter: nf_tables: fix pointer math issue in nft_byteorder

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Date: Fri,  2 Feb 2024 12:11:21 +0530
From: Ajay Kaher <ajay.kaher@...adcom.com>
To: stable@...r.kernel.org,
	gregkh@...uxfoundation.org
Cc: pablo@...filter.org,
	kadlec@...filter.org,
	fw@...len.de,
	davem@...emloft.net,
	netfilter-devel@...r.kernel.org,
	coreteam@...filter.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	alexey.makhalov@...adcom.com,
	florian.fainelli@...adcom.com,
	vasavi.sirnapalli@...adcom.com,
	Dan Carpenter <dan.carpenter@...aro.org>,
	Sasha Levin <sashal@...nel.org>,
	Ajay Kaher <ajay.kaher@...adcom.com>
Subject: [PATCH v5.10.y] netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval()

From: Dan Carpenter <dan.carpenter@...aro.org>

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 <dan.carpenter@...aro.org>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
[Ajay: Modified to apply on v5.10.y]
Signed-off-by: Ajay Kaher <ajay.kaher@...adcom.com>
---
 include/net/netfilter/nf_tables.h | 4 ++--
 net/netfilter/nft_byteorder.c     | 5 +++--
 net/netfilter/nft_meta.c          | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 2237657..2da11d8 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -142,9 +142,9 @@ static inline u16 nft_reg_load16(const u32 *sreg)
 	return *(u16 *)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)
diff --git a/net/netfilter/nft_byteorder.c b/net/netfilter/nft_byteorder.c
index 7b0b8fe..9d250bd 100644
--- a/net/netfilter/nft_byteorder.c
+++ b/net/netfilter/nft_byteorder.c
@@ -38,20 +38,21 @@ 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], be64_to_cpu(src64));
+				nft_reg_store64(&dst64[i], be64_to_cpu(src64));
 			}
 			break;
 		case NFT_BYTEORDER_HTON:
 			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;
 		}
diff --git a/net/netfilter/nft_meta.c b/net/netfilter/nft_meta.c
index 44d9b38..cb5bb0e 100644
--- a/net/netfilter/nft_meta.c
+++ b/net/netfilter/nft_meta.c
@@ -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());
-- 
2.7.4