From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 9CC3B4B66E8 for ; Thu, 3 Sep 2026 14:24:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788445490; cv=none; b=deOAOXrZ97MLblNKw6X+cPh4RDwSNhkC/PLqREBTIACXu3R9yj7lL+M3OPbmihQzKnX3PmjlbB8Ep7WXUzDOV9zmj0w7TcPoASOVlJRVYuKuc5pvpTM5knVeDykYCjAfUsozSM4c4efVO2enltIyqqxzZiZlhsjsCBzq7BzGMi0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788445490; c=relaxed/simple; bh=DxmKPiUge5SGqNrGUv0uYwyRfeIehz3PokhZZ4xbp/U=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=qfKmhstP71d+b9PfCgUj1bOiH7V67rutGKwA7tOtoe3RGk7xtXwEncNN7zqSVw3pA3H3xDPI2kqyBVX2gLJixPD4irg5y9EkHyflNZD+mobkREnvs4UQKc2ExEV2OK4er3kj2iSz8wgH3kAWQTPx2LHQdYOCNJtOy9nplGhzwS0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=IFXs2ycg; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="IFXs2ycg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6D551F00A3D; Thu, 3 Sep 2026 14:24:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788445487; bh=YUvf5Um4G2y8LoRmnXr4bAvvy7ldk3dc0/PceuU8WM0=; h=Subject:To:Cc:From:Date; b=IFXs2ycgjQX5gUWt0ZQgPL797a4prFc94OzlYWfGF4X2CQkEXdnEBo0PXdX7KrRYX CadHKvf7mib2A8Olza3ewImjNV3X0JAXlAse5LzMNwLJnUp/D1hAQ1sirUKjQAfR4Y RIwNbodDH9f4izmxoZ+Ynce8A8BJ4ZhpMqJ1vc9g= Subject: FAILED: patch "[PATCH] ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()" failed to apply to 6.1-stable tree To: andrea.mayer@uniroma2.it,horms@kernel.org,kuba@kernel.org,xmei5@asu.edu Cc: From: Date: Thu, 03 Sep 2026 16:00:50 +0200 Message-ID: <2026090350-camcorder-skillful-ef4f@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x f826df95332c07380206dbd54178b6eefb311aba # git commit -s git send-email --to '' --in-reply-to '2026090350-camcorder-skillful-ef4f@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From f826df95332c07380206dbd54178b6eefb311aba Mon Sep 17 00:00:00 2001 From: Andrea Mayer Date: Mon, 17 Aug 2026 15:26:44 +0200 Subject: [PATCH] ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv() ipv6_rpl_srh_rcv() dereferences idev from __in6_dev_get() without a NULL check when reading idev->cnf.rpl_seg_enabled. When the device's MTU drops below IPV6_MIN_MTU, addrconf_ifdown() clears dev->ip6_ptr through RCU_INIT_POINTER(). A packet that passed the idev check in ip6_rcv_core() can then reach ipv6_rpl_srh_rcv() with dev->ip6_ptr already NULL. Reproduced by flooding the receiving interface with ping6 traffic while flapping its MTU between 1500 and 1200: BUG: KASAN: null-ptr-deref in ipv6_rpl_srh_rcv+0xb3/0x1070 Read of size 4 at addr 00000000000006b4 by task ping6/394 CPU: 2 UID: 0 PID: 394 Comm: ping6 Not tainted 7.2.0-rc7-micro-vm-dev-00095-g24ef02f934ee #240 PREEMPT(full) Call Trace: kasan_report+0xc6/0x100 ipv6_rpl_srh_rcv+0xb3/0x1070 ip6_protocol_deliver_rcu+0x759/0x9a0 ip6_input_finish+0xa8/0x1b0 ip6_input+0xe1/0x490 ipv6_rcv+0x33d/0x460 __netif_receive_skb_one_core+0xd6/0x130 process_backlog+0x2cc/0xa00 __napi_poll.constprop.0+0x56/0x270 net_rx_action+0x327/0x730 handle_softirqs+0x11e/0x630 do_softirq+0xb3/0xf0 Both ipv6_rpl_srh_rcv() and ipv6_srh_rcv() are called only from ipv6_rthdr_rcv(), which already has an idev lookup. Fix the NULL dereference on the RPL path by checking idev in ipv6_rthdr_rcv(), before it calls either function. The callees take idev as an argument and no longer call __in6_dev_get(), so the packet is now dropped in one place, with SKB_DROP_REASON_IPV6DISABLED on both paths. Fixes: 8610c7c6e3bd ("net: ipv6: add support for rpl sr exthdr") Cc: stable@vger.kernel.org Signed-off-by: Andrea Mayer Tested-by: Xiang Mei Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260817132644.2223-1-andrea.mayer@uniroma2.it Signed-off-by: Jakub Kicinski diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c index 9c677eb1d1a6..51941ad656a3 100644 --- a/net/ipv6/exthdrs.c +++ b/net/ipv6/exthdrs.c @@ -368,23 +368,16 @@ static void seg6_update_csum(struct sk_buff *skb) (__be32 *)addr); } -static int ipv6_srh_rcv(struct sk_buff *skb) +static int ipv6_srh_rcv(struct sk_buff *skb, struct inet6_dev *idev) { struct inet6_skb_parm *opt = IP6CB(skb); struct net *net = dev_net(skb->dev); struct ipv6_sr_hdr *hdr; - struct inet6_dev *idev; struct in6_addr *addr; int accept_seg6; hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb); - idev = __in6_dev_get(skb->dev); - if (!idev) { - kfree_skb(skb); - return -1; - } - accept_seg6 = min(READ_ONCE(net->ipv6.devconf_all->seg6_enabled), READ_ONCE(idev->cnf.seg6_enabled)); @@ -485,12 +478,11 @@ static int ipv6_srh_rcv(struct sk_buff *skb) return -1; } -static int ipv6_rpl_srh_rcv(struct sk_buff *skb) +static int ipv6_rpl_srh_rcv(struct sk_buff *skb, struct inet6_dev *idev) { struct ipv6_rpl_sr_hdr *hdr, *ohdr, *chdr; struct inet6_skb_parm *opt = IP6CB(skb); struct net *net = dev_net(skb->dev); - struct inet6_dev *idev; struct ipv6hdr *oldhdr; unsigned int chdr_len; unsigned char *buf; @@ -499,8 +491,6 @@ static int ipv6_rpl_srh_rcv(struct sk_buff *skb) u64 n = 0; u32 r; - idev = __in6_dev_get(skb->dev); - accept_rpl_seg = min(READ_ONCE(net->ipv6.devconf_all->rpl_seg_enabled), READ_ONCE(idev->cnf.rpl_seg_enabled)); if (!accept_rpl_seg) { @@ -689,10 +679,14 @@ static int ipv6_rthdr_rcv(struct sk_buff *skb) switch (hdr->type) { case IPV6_SRCRT_TYPE_4: /* segment routing */ - return ipv6_srh_rcv(skb); + if (!idev) + goto disabled; + return ipv6_srh_rcv(skb, idev); case IPV6_SRCRT_TYPE_3: /* rpl segment routing */ - return ipv6_rpl_srh_rcv(skb); + if (!idev) + goto disabled; + return ipv6_rpl_srh_rcv(skb, idev); default: break; } @@ -837,6 +831,10 @@ static int ipv6_rthdr_rcv(struct sk_buff *skb) icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, (&hdr->type) - skb_network_header(skb)); return -1; + +disabled: + kfree_skb_reason(skb, SKB_DROP_REASON_IPV6DISABLED); + return -1; } static const struct inet6_protocol rthdr_protocol = {