diff mbox series

[net,1/6] netfilter: nftables: exthdr: fix 4-byte stack OOB write

Message ID 20230906162525.11079-2-fw@strlen.de
State Not Applicable, archived
Headers show
Series [net,1/6] netfilter: nftables: exthdr: fix 4-byte stack OOB write | expand

Commit Message

Florian Westphal Sept. 6, 2023, 4:25 p.m. UTC 
If priv->len is a multiple of 4, then dst[len / 4] can write past
the destination array which leads to stack corruption.

This construct is necessary to clean the remainder of the register
in case ->len is NOT a multiple of the register size, so make it
conditional just like nft_payload.c does.

The bug was added in 4.1 cycle and then copied/inherited when
tcp/sctp and ip option support was added.

Bug reported by Zero Day Initiative project (ZDI-CAN-21950,
ZDI-CAN-21951, ZDI-CAN-21961).

Fixes: 49499c3e6e18 ("netfilter: nf_tables: switch registers to 32 bit addressing")
Fixes: 935b7f643018 ("netfilter: nft_exthdr: add TCP option matching")
Fixes: 133dc203d77d ("netfilter: nft_exthdr: Support SCTP chunks")
Fixes: dbb5281a1f84 ("netfilter: nf_tables: add support for matching IPv4 options")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nft_exthdr.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

Comments

patchwork-bot+netdevbpf@kernel.org Sept. 7, 2023, 10:40 a.m. UTC | #1 
Hello:

This series was applied to netdev/net.git (main)
by Florian Westphal <fw@strlen.de>:

On Wed,  6 Sep 2023 18:25:07 +0200 you wrote:
> If priv->len is a multiple of 4, then dst[len / 4] can write past
> the destination array which leads to stack corruption.
> 
> This construct is necessary to clean the remainder of the register
> in case ->len is NOT a multiple of the register size, so make it
> conditional just like nft_payload.c does.
> 
> [...]

Here is the summary with links:
  - [net,1/6] netfilter: nftables: exthdr: fix 4-byte stack OOB write
    https://git.kernel.org/netdev/net/c/fd94d9dadee5
  - [net,2/6] netfilter: nfnetlink_osf: avoid OOB read
    https://git.kernel.org/netdev/net/c/f4f8a7803119
  - [net,3/6] netfilter: nf_tables: uapi: Describe NFTA_RULE_CHAIN_ID
    https://git.kernel.org/netdev/net/c/fdc04cc2d5fd
  - [net,4/6] netfilter: nft_set_rbtree: skip sync GC for new elements in this transaction
    https://git.kernel.org/netdev/net/c/2ee52ae94baa
  - [net,5/6] netfilter: ipset: add the missing IP_SET_HASH_WITH_NET0 macro for ip_set_hash_netportnet.c
    https://git.kernel.org/netdev/net/c/050d91c03b28
  - [net,6/6] netfilter: nf_tables: Unbreak audit log reset
    https://git.kernel.org/netdev/net/c/9b5ba5c9c510

You are awesome, thank you!
diff mbox series

Patch

diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index a9844eefedeb..3fbaa7bf41f9 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -35,6 +35,14 @@  static unsigned int optlen(const u8 *opt, unsigned int offset)
 		return opt[offset + 1];
 }
 
+static int nft_skb_copy_to_reg(const struct sk_buff *skb, int offset, u32 *dest, unsigned int len)
+{
+	if (len % NFT_REG32_SIZE)
+		dest[len / NFT_REG32_SIZE] = 0;
+
+	return skb_copy_bits(skb, offset, dest, len);
+}
+
 static void nft_exthdr_ipv6_eval(const struct nft_expr *expr,
 				 struct nft_regs *regs,
 				 const struct nft_pktinfo *pkt)
@@ -56,8 +64,7 @@  static void nft_exthdr_ipv6_eval(const struct nft_expr *expr,
 	}
 	offset += priv->offset;
 
-	dest[priv->len / NFT_REG32_SIZE] = 0;
-	if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
+	if (nft_skb_copy_to_reg(pkt->skb, offset, dest, priv->len) < 0)
 		goto err;
 	return;
 err:
@@ -153,8 +160,7 @@  static void nft_exthdr_ipv4_eval(const struct nft_expr *expr,
 	}
 	offset += priv->offset;
 
-	dest[priv->len / NFT_REG32_SIZE] = 0;
-	if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
+	if (nft_skb_copy_to_reg(pkt->skb, offset, dest, priv->len) < 0)
 		goto err;
 	return;
 err:
@@ -210,7 +216,8 @@  static void nft_exthdr_tcp_eval(const struct nft_expr *expr,
 		if (priv->flags & NFT_EXTHDR_F_PRESENT) {
 			*dest = 1;
 		} else {
-			dest[priv->len / NFT_REG32_SIZE] = 0;
+			if (priv->len % NFT_REG32_SIZE)
+				dest[priv->len / NFT_REG32_SIZE] = 0;
 			memcpy(dest, opt + offset, priv->len);
 		}
 
@@ -388,9 +395,8 @@  static void nft_exthdr_sctp_eval(const struct nft_expr *expr,
 			    offset + ntohs(sch->length) > pkt->skb->len)
 				break;
 
-			dest[priv->len / NFT_REG32_SIZE] = 0;
-			if (skb_copy_bits(pkt->skb, offset + priv->offset,
-					  dest, priv->len) < 0)
+			if (nft_skb_copy_to_reg(pkt->skb, offset + priv->offset,
+						dest, priv->len) < 0)
 				break;
 			return;
 		}