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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: "Kito Xu (veritas501)" <hxzene@gmail.com>
Cc: Florian Westphal <fw@strlen.de>, Phil Sutter <phil@nwl.cc>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Simon Horman <horms@kernel.org>,
	Fernando Fernandez Mancera <ffmancera@riseup.net>,
	netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] netfilter: nfnetlink_osf: fix null-ptr-deref in nf_osf_ttl
Date: Tue, 14 Apr 2026 11:19:50 +0200	[thread overview]
Message-ID: <ad4GtgPqTcXl8hUC@chamomile> (raw)
In-Reply-To: <20260414074556.2512750-1-hxzene@gmail.com>

On Tue, Apr 14, 2026 at 03:45:56PM +0800, Kito Xu (veritas501) wrote:
> diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c
> index d64ce21c7b55..85dbd47dbbd4 100644
> --- a/net/netfilter/nfnetlink_osf.c
> +++ b/net/netfilter/nfnetlink_osf.c
> @@ -43,6 +43,9 @@ static inline int nf_osf_ttl(const struct sk_buff *skb,
>  	else if (ip->ttl <= f_ttl)
>  		return 1;
>  
> +	if (!in_dev)
> +		return 0;
> +

I suggest you add this check a bit earlier:

diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c
index 5d15651c74f0..e8069f4e139b 100644
--- a/net/netfilter/nfnetlink_osf.c
+++ b/net/netfilter/nfnetlink_osf.c
@@ -36,6 +36,9 @@ static inline int nf_osf_ttl(const struct sk_buff *skb,
        const struct in_ifaddr *ifa;
        int ret = 0;
 
+       if (!in_dev)
+               return 0;
+
        if (ttl_check == NF_OSF_TTL_TRUE)
                return ip->ttl == f_ttl;
        if (ttl_check == NF_OSF_TTL_NOCHECK)
@@ -43,9 +46,6 @@ static inline int nf_osf_ttl(const struct sk_buff *skb,
        else if (ip->ttl <= f_ttl)
                return 1;
 
-       if (!in_dev)
-               return 0;
-
        in_dev_for_each_ifa_rcu(ifa, in_dev) {
                if (inet_ifa_match(ip->saddr, ifa)) {
                        ret = (ip->ttl == f_ttl);

Thanks!

  parent reply	other threads:[~2026-04-14  9:19 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-14  7:45 [PATCH] netfilter: nfnetlink_osf: fix null-ptr-deref in nf_osf_ttl Kito Xu (veritas501)
2026-04-14  8:22 ` Pablo Neira Ayuso
2026-04-14  8:37   ` Kito Xu (veritas501)
2026-04-14  8:55     ` Pablo Neira Ayuso
2026-04-14  9:19 ` Pablo Neira Ayuso [this message]
2026-04-14 10:49 ` [PATCH v2] " Kito Xu (veritas501)
2026-04-14 11:14   ` Florian Westphal
2026-04-14 11:50   ` Fernando Fernandez Mancera

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