* [PATCH -stable,5.4] netfilter: nftables: exthdr: fix 4-byte stack OOB write
@ 2024-06-13 17:13 Pablo Neira Ayuso
0 siblings, 0 replies; 3+ messages in thread
From: Pablo Neira Ayuso @ 2024-06-13 17:13 UTC (permalink / raw)
To: netfilter-devel; +Cc: gregkh, stable, sashal
From: Florian Westphal <fw@strlen.de>
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@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
Hi Greg, Sasha,
This backport is missing in 5.4, please apply to -stable. Thanks.
net/netfilter/nft_exthdr.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index 670dd146fb2b..ca268293cfa1 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -33,6 +33,14 @@ 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)
@@ -54,8 +62,7 @@ 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:
@@ -151,8 +158,7 @@ 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:
@@ -208,7 +214,8 @@ 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);
}
--
2.30.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH -stable,5.4] netfilter: nftables: exthdr: fix 4-byte stack OOB write
@ 2024-06-13 17:14 Pablo Neira Ayuso
2024-06-19 10:50 ` Greg KH
0 siblings, 1 reply; 3+ messages in thread
From: Pablo Neira Ayuso @ 2024-06-13 17:14 UTC (permalink / raw)
To: netfilter-devel; +Cc: sashal, gregkh, stable
From: Florian Westphal <fw@strlen.de>
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@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
Hi Greg, Sasha,
This backport is missing in 5.4, please apply to -stable. Thanks.
net/netfilter/nft_exthdr.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index 670dd146fb2b..ca268293cfa1 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -33,6 +33,14 @@ 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)
@@ -54,8 +62,7 @@ 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:
@@ -151,8 +158,7 @@ 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:
@@ -208,7 +214,8 @@ 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);
}
--
2.30.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH -stable,5.4] netfilter: nftables: exthdr: fix 4-byte stack OOB write
2024-06-13 17:14 [PATCH -stable,5.4] netfilter: nftables: exthdr: fix 4-byte stack OOB write Pablo Neira Ayuso
@ 2024-06-19 10:50 ` Greg KH
0 siblings, 0 replies; 3+ messages in thread
From: Greg KH @ 2024-06-19 10:50 UTC (permalink / raw)
To: Pablo Neira Ayuso; +Cc: netfilter-devel, sashal, stable
On Thu, Jun 13, 2024 at 07:14:55PM +0200, Pablo Neira Ayuso wrote:
> From: Florian Westphal <fw@strlen.de>
>
> 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@strlen.de>
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
> Hi Greg, Sasha,
>
> This backport is missing in 5.4, please apply to -stable. Thanks.
>
> net/netfilter/nft_exthdr.c | 17 ++++++++++++-----
> 1 file changed, 12 insertions(+), 5 deletions(-)
Now queued up, thanks.
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread
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