This is a note to let you know that I've just added the patch titled
netfilter: nftables: exthdr: fix 4-byte stack OOB write
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-nftables-exthdr-fix-4-byte-stack-oob-write.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fd94d9dadee58e09b49075240fe83423eb1dcd36 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@xxxxxxxxx>
Date: Tue, 5 Sep 2023 23:13:56 +0200
Subject: netfilter: nftables: exthdr: fix 4-byte stack OOB write
From: Florian Westphal <fw@xxxxxxxxx>
commit fd94d9dadee58e09b49075240fe83423eb1dcd36 upstream.
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@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/netfilter/nft_exthdr.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -35,6 +35,14 @@ static unsigned int optlen(const u8 *opt
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 s
}
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 s
}
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 st
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 s
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;
}
Patches currently in stable-queue which might be from fw@xxxxxxxxx are
queue-5.10/netfilter-nf_tables-defer-gc-run-if-previous-batch-i.patch
queue-5.10/netfilter-ipset-fix-race-between-ipset_cmd_create-an.patch
queue-5.10/netfilter-nf_tables-fix-kdoc-warnings-after-gc-rework.patch
queue-5.10/netfilter-exthdr-add-support-for-tcp-option-removal.patch
queue-5.10/netfilter-nft_exthdr-fix-for-unsafe-packet-data-read.patch
queue-5.10/netfilter-nft_set_rbtree-skip-sync-gc-for-new-elemen.patch
queue-5.10/netfilter-nf_tables-add-and-use-nft_sk-helper.patch
queue-5.10/netfilter-nf_tables-fix-false-positive-lockdep-splat.patch
queue-5.10/netfilter-nf_tables-gc-transaction-race-with-netns-d.patch
queue-5.10/netfilter-nf_tables-don-t-fail-inserts-if-duplicate-.patch
queue-5.10/netfilter-nf_tables-add-and-use-nft_thoff-helper.patch
queue-5.10/netfilter-handle-the-connecting-collision-properly-i.patch
queue-5.10/netfilter-nf_tables-nft_set_rbtree-fix-spurious-inse.patch
queue-5.10/netfilter-nf_tables-fix-memleak-when-more-than-255-e.patch
queue-5.10/netfilter-nf_tables-don-t-skip-expired-elements-duri.patch
queue-5.10/netfilter-nf_tables-fix-gc-transaction-races-with-ne.patch
queue-5.10/netfilter-nftables-exthdr-fix-4-byte-stack-oob-write.patch
