[{"id":3677135,"web_url":"http://patchwork.ozlabs.org/comment/3677135/","msgid":"","list_archive_url":null,"date":"2026-04-14T11:14:11","subject":"Re: [PATCH v2] netfilter: nfnetlink_osf: fix null-ptr-deref in\n nf_osf_ttl","submitter":{"id":1025,"url":"http://patchwork.ozlabs.org/api/people/1025/","name":"Florian Westphal","email":"fw@strlen.de"},"content":"Kito Xu (veritas501) wrote:\n> nf_osf_ttl() calls __in_dev_get_rcu(skb->dev) and passes the result\n> to in_dev_for_each_ifa_rcu() without checking for NULL. When the\n> receiving device has no IPv4 configuration (ip_ptr is NULL),\n> __in_dev_get_rcu() returns NULL and in_dev_for_each_ifa_rcu()\n> dereferences it unconditionally, causing a kernel crash.\n> \n> This can happen when a packet arrives on a device that has had its\n> IPv4 configuration removed (e.g., MTU set below IPV4_MIN_MTU causing\n> inetdev_destroy) or on a device that was never assigned an IPv4\n> address, while an xt_osf or nft_osf rule with TTL_LESS mode is\n> active and the packet TTL exceeds the fingerprint TTL.\n> \n> Add a NULL check for in_dev before using it. When in_dev is NULL,\n> return 0 (no match) since source-address locality cannot be\n> determined without IPv4 addresses on the device.\n> \n> KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n> RIP: 0010:nf_osf_match_one+0x204/0xa70\n> Call Trace:\n> \n> nf_osf_match+0x2f8/0x780\n> xt_osf_match_packet+0x11c/0x1f0\n> ipt_do_table+0x7fe/0x12b0\n> nf_hook_slow+0xac/0x1e0\n> ip_rcv+0x123/0x370\n> __netif_receive_skb_one_core+0x166/0x1b0\n> process_backlog+0x197/0x590\n> __napi_poll+0xa1/0x540\n> net_rx_action+0x401/0xd80\n> handle_softirqs+0x19f/0x610\n> \n> \n> Fixes: a218dc82f0b5 (\"netfilter: nft_osf: Add ttl option support\")\n> Suggested-by: Pablo Neira Ayuso \n> Signed-off-by: Kito Xu (veritas501) \n\nThe other __in_dev_get_rcu() callers in netfilter check return value, so:\n\nReviewed-by: Florian Westphal ","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","netfilter-devel@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.105.105.114; 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Tue, 14 Apr 2026 13:14:11 +0200 (CEST)"],"ARC-Seal":"i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1776165255; cv=none;\n b=F73oiXm30CFlLiTWSs/uCGl3SvfwKfsfxWCNLJJfe7pDyMnObjDEHO3oxGK+i9Qfd427dUbQ8JORtvz+FvnvjXYXLoriXHSPQxhGDhgyKlq88ncbeP9AwCvfOIQt6XQv/IbNzqn4Qmcrl0rE0N9qVPsp4ul1woPIZVGASD0wDvg=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1776165255; c=relaxed/simple;\n\tbh=09uiMZRs7r7SYhGOfTyq/qJWTKsO/uLe3Dd56LS2Js4=;\n\th=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version:\n\t Content-Type:Content-Disposition:In-Reply-To;\n b=R4JfR/CtQII0adH0ULXIUO8fj9KR6TMpdUe//GDwDSdBbOAZmJtYjCreTTR1tQV8FVnkF9JbjhOEFDZmiJyVGoyX9b8xFMoRAntENea5uUehAR20jcv11G2biNfiFygQhDIsV3WOUn5rdm7grhobEUBG+mhIEnadQYGnyQN3MqI=","ARC-Authentication-Results":"i=1; smtp.subspace.kernel.org;\n dmarc=none (p=none dis=none) header.from=strlen.de;\n spf=pass smtp.mailfrom=strlen.de; arc=none smtp.client-ip=91.216.245.30","Date":"Tue, 14 Apr 2026 13:14:11 +0200","From":"Florian Westphal ","To":"\"Kito Xu (veritas501)\" ","Cc":"pablo@netfilter.org, coreteam@netfilter.org, davem@davemloft.net,\n\tedumazet@google.com, ffmancera@riseup.net, horms@kernel.org,\n\tkuba@kernel.org, linux-kernel@vger.kernel.org,\n\tnetdev@vger.kernel.org, netfilter-devel@vger.kernel.org,\n\tpabeni@redhat.com, phil@nwl.cc","Subject":"Re: [PATCH v2] netfilter: nfnetlink_osf: fix null-ptr-deref in\n nf_osf_ttl","Message-ID":"","References":"<20260414074556.2512750-1-hxzene@gmail.com>\n <20260414104900.2617863-1-hxzene@gmail.com>","Precedence":"bulk","X-Mailing-List":"netfilter-devel@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20260414104900.2617863-1-hxzene@gmail.com>"}},{"id":3677153,"web_url":"http://patchwork.ozlabs.org/comment/3677153/","msgid":"<818aa828-7a16-4f89-930d-c38f42f7a0a6@suse.de>","list_archive_url":null,"date":"2026-04-14T11:50:45","subject":"Re: [PATCH v2] netfilter: nfnetlink_osf: fix null-ptr-deref in\n nf_osf_ttl","submitter":{"id":90904,"url":"http://patchwork.ozlabs.org/api/people/90904/","name":"Fernando Fernandez Mancera","email":"fmancera@suse.de"},"content":"On 4/14/26 12:49 PM, Kito Xu (veritas501) wrote:\n> nf_osf_ttl() calls __in_dev_get_rcu(skb->dev) and passes the result\n> to in_dev_for_each_ifa_rcu() without checking for NULL. When the\n> receiving device has no IPv4 configuration (ip_ptr is NULL),\n> __in_dev_get_rcu() returns NULL and in_dev_for_each_ifa_rcu()\n> dereferences it unconditionally, causing a kernel crash.\n> \n> This can happen when a packet arrives on a device that has had its\n> IPv4 configuration removed (e.g., MTU set below IPV4_MIN_MTU causing\n> inetdev_destroy) or on a device that was never assigned an IPv4\n> address, while an xt_osf or nft_osf rule with TTL_LESS mode is\n> active and the packet TTL exceeds the fingerprint TTL.\n> \n> Add a NULL check for in_dev before using it. When in_dev is NULL,\n> return 0 (no match) since source-address locality cannot be\n> determined without IPv4 addresses on the device.\n> \n> KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n> RIP: 0010:nf_osf_match_one+0x204/0xa70\n> Call Trace:\n> \n> nf_osf_match+0x2f8/0x780\n> xt_osf_match_packet+0x11c/0x1f0\n> ipt_do_table+0x7fe/0x12b0\n> nf_hook_slow+0xac/0x1e0\n> ip_rcv+0x123/0x370\n> __netif_receive_skb_one_core+0x166/0x1b0\n> process_backlog+0x197/0x590\n> __napi_poll+0xa1/0x540\n> net_rx_action+0x401/0xd80\n> handle_softirqs+0x19f/0x610\n> \n> \n> Fixes: a218dc82f0b5 (\"netfilter: nft_osf: Add ttl option support\")\n> Suggested-by: Pablo Neira Ayuso \n> Signed-off-by: Kito Xu (veritas501) \n\nReviewed-by: Fernando Fernandez Mancera \n\nThanks !","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","netfilter-devel@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=suse.de header.i=@suse.de header.a=rsa-sha256\n header.s=susede2_rsa header.b=JRMoU+YD;\n\tdkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=GZAKv62o;\n\tdkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de\n header.a=rsa-sha256 header.s=susede2_rsa header.b=bEtBj5ld;\n\tdkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256\n header.s=susede2_ed25519 header.b=6H74mJFu;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; 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