From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8C92629AB1A; Mon, 6 Apr 2026 10:48:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775472514; cv=none; b=BFT5FhCGP5yh5ItIy4/oOXLLSYjhCAaPcr0KBVHI1jYGGx2Qd0FYgUJ0cT2185ej92/SZqcJUDjWQMl0WXimFGkitNIn3aLcO5pu4a65w1ON0Ygko6UDO7uveerOYq6ZdN+IyrLIIaftl7Og+Ajh1nE5gSDIiOdTnQeO9WXO+k8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775472514; c=relaxed/simple; bh=wRknuBZkIqancIXrcQUTPJJqXUPLtdGU/WPeK77mUCs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=iFUoyJyWcCv0He1LjQ+p2xaMPfajB5WFg7+rzp2ftuytxopUg92Ic28E7nWy69AqCdu5xb50m4S5YxCk7+DyqVFwX69muwcEyL4i5inRD0+KNKy/xXtc2DffJNZb/SWOefJkjqwhbSILPz6YVc7bgg/iwLCbdPgEgGuyEkUKsg0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=iT1ynYE6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="iT1ynYE6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA0BAC4CEF7; Mon, 6 Apr 2026 10:48:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775472514; bh=wRknuBZkIqancIXrcQUTPJJqXUPLtdGU/WPeK77mUCs=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=iT1ynYE6p+F7HyEqgt2dXGYoKGYtu3h9lZ+AiaWJDtul1mTFwoZceCGyVHY5+seSH wmRzDsPYRCmgjbc+J3XqqDJnpTI1+K0FbK0OnVXOK9yVvd+7QqpAz6m5VY9SKFH84X 1DEOnQfvtu3PLkVhiQ6tuNEWHe1sNIY/7pAfJXr8KYyOO0JZ7coE8Vv8yJ6g6Xq7qB E6HJFxPM91eOYIvylJfjEBtgfx8Ks1lD8aTV+m8yBVw8hyqwUI927fWXkfevWHPOnF 3TvEZzG4sET7gg7iQINg227rqTj6irqA/eVAbU2zpqurl60ZRp87EcwkOQLH8AbEzV R4YOCeDhKaz1Q== Message-ID: Date: Mon, 6 Apr 2026 12:48:28 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH net] ipv4: icmp: fix null-ptr-deref in icmp_build_probe(): manual merge Content-Language: fr To: Yiqi Sun Cc: horms@kernel.org, netdev@vger.kernel.org, davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, Mark Brown , linux-next@vger.kernel.org References: <20260402070419.2291578-1-sunyiqixm@gmail.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hello, +cc linux-next On 02/04/2026 09:04, Yiqi Sun wrote: > ipv6_stub->ipv6_dev_find() may return ERR_PTR(-EAFNOSUPPORT) when the > IPv6 stack is not active (CONFIG_IPV6=m and not loaded), and passing > this error pointer to dev_hold() will cause a kernel crash with > null-ptr-deref. > > Instead, silently discard the request. RFC 8335 does not appear to > define a specific response for the case where an IPv6 interface > identifier is syntactically valid but the implementation cannot perform > the lookup at runtime, and silently dropping the request may safer than > misreporting "No Such Interface". FYI, we got a small conflict when merging 'net' in 'net-next' in the MPTCP tree due to this patch applied in 'net': fde29fd93493 ("ipv4: icmp: fix null-ptr-deref in icmp_build_probe()") and this one from 'net-next': d98adfbdd5c0 ("ipv4: drop ipv6_stub usage and use direct function calls") ----- Generic Message ----- The best is to avoid conflicts between 'net' and 'net-next' trees but if they cannot be avoided when preparing patches, a note about how to fix them is much appreciated. The conflict has been resolved on our side [1] and the resolution we suggest is attached to this email. Please report any issues linked to this conflict resolution as it might be used by others. If you worked on the mentioned patches, don't hesitate to ACK this conflict resolution. --------------------------- Rerere cache is available in [2]. 1: https://github.com/multipath-tcp/mptcp_net-next/commit/c14d8597c9a0 2: https://github.com/multipath-tcp/mptcp-upstream-rr-cache/commit/d4699ea > diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c > index 568bd1e95d44..d294666c68d9 100644 > --- a/net/ipv4/icmp.c > +++ b/net/ipv4/icmp.c (...) > bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) > @@ -1346,6 +1347,13 @@ bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) > if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) > goto send_mal_query; > dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); The conflict was in the context: the commit in net-next modified this line above, while the one in net added this block below. > + /* > + * If IPv6 identifier lookup is unavailable, silently > + * discard the request instead of misreporting NO_IF. > + */ > + if (IS_ERR(dev)) > + return false; > + > dev_hold(dev); > break; > #endif ----------------------- 8< ----------------------- diff --cc net/ipv4/icmp.c index 2f4fac22d1ab,4e2a6c70dcd8..f1c715cc3800 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@@ -1342,7 -1345,14 +1342,14 @@@ bool icmp_build_probe(struct sk_buff *s case ICMP_AFI_IP6: if (iio->ident.addr.ctype3_hdr.addrlen != sizeof(struct in6_addr)) goto send_mal_query; - dev = ipv6_stub->ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); + dev = ipv6_dev_find(net, &iio->ident.addr.ip_addr.ipv6_addr, dev); + /* + * If IPv6 identifier lookup is unavailable, silently + * discard the request instead of misreporting NO_IF. + */ + if (IS_ERR(dev)) + return false; + dev_hold(dev); break; #endif ----------------------- 8< ----------------------- Cheers, Matt -- Sponsored by the NGI0 Core fund.