{"id":2219560,"url":"http://patchwork.ozlabs.org/api/patches/2219560/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/ac-w6e33txkgTRJj@strlen.de/","project":{"id":26,"url":"http://patchwork.ozlabs.org/api/projects/26/?format=json","name":"Netfilter Development","link_name":"netfilter-devel","list_id":"netfilter-devel.vger.kernel.org","list_email":"netfilter-devel@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"","list_archive_url":null,"date":"2026-04-03T12:22:01","name":"nfnetlink_queue crashes kernel","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"4f639ecd03d1ed947db431b44444285916b68b18","submitter":{"id":1025,"url":"http://patchwork.ozlabs.org/api/people/1025/?format=json","name":"Florian Westphal","email":"fw@strlen.de"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/ac-w6e33txkgTRJj@strlen.de/mbox/","series":[{"id":498622,"url":"http://patchwork.ozlabs.org/api/series/498622/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=498622","date":"2026-04-03T12:22:01","name":"nfnetlink_queue crashes kernel","version":1,"mbox":"http://patchwork.ozlabs.org/series/498622/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2219560/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2219560/checks/","tags":{},"related":[],"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=172.234.253.10; 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arc=none smtp.client-ip=91.216.245.30","Date":"Fri, 3 Apr 2026 14:22:01 +0200","From":"Florian Westphal ","To":"Scott Mitchell ","Cc":"netfilter-devel@vger.kernel.org","Subject":"nfnetlink_queue crashes kernel","Message-ID":"","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","Content-Transfer-Encoding":"quoted-printable"},"content":"Hello,\n\nnfnetlink_queue is currently broken in at least two ways.\n1). kernel will crash under pressure because\n struct nf_queue_entry is freed via kfree, but parallel\n cpu can still observe this while walking the (global) rhashtable.\n\n2) a4400a5b343d (\"netfilter: nfnetlink_queue: nfqnl_instance GFP_ATOMIC -> GFP_KERNEL_ACCOUNT allocation\") should have updated the spinlock to use the _bh variant, if the queue exists we risk deadlock via softirq recursion.\n\nMinimal fix, that I am not a fan of:\n\n\n\n\nA probably better fix is to make the rhashtable perqueue, which is\nmuch more intrusive at this late stage.\n\nI prefer to revert both changes and not accept a reworked hashtable\nuntil we have an extension to nft_queue.sh selftest.\n\nAnything using queue balancing (pacing packets to n queues) with\nenough streams to have parallel invocation of the rhashtable should\ndemonstrate the crash.\n\nThoughts?","diff":"diff --git a/include/net/netfilter/nf_queue.h b/include/net/netfilter/nf_queue.h\n--- a/include/net/netfilter/nf_queue.h\n+++ b/include/net/netfilter/nf_queue.h\n@@ -24,6 +24,7 @@ struct nf_queue_entry {\n \tbool\t\t\tnf_ct_is_unconfirmed;\n \tu16\t\t\tsize; /* sizeof(entry) + saved route keys */\n \tu16\t\t\tqueue_num;\n+\tstruct rcu_head\t\thead;\n \n \t/* extra space to store route keys */\n };\ndiff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c\nindex 7f12e56e6e52..385d1fe704ae 100644\n--- a/net/netfilter/nf_queue.c\n+++ b/net/netfilter/nf_queue.c\n@@ -74,7 +74,7 @@ static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)\n void nf_queue_entry_free(struct nf_queue_entry *entry)\n {\n \tnf_queue_entry_release_refs(entry);\n-\tkfree(entry);\n+\tkfree_rcu(entry, head);\n }\n EXPORT_SYMBOL_GPL(nf_queue_entry_free);\n \ndiff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c\nindex 47f7f62906e2..fc44ea4e5128 100644\n--- a/net/netfilter/nfnetlink_queue.c\n+++ b/net/netfilter/nfnetlink_queue.c\n@@ -190,7 +190,7 @@ instance_create(struct nfnl_queue_net *q, u_int16_t queue_num, u32 portid)\n \tspin_lock_init(&inst->lock);\n \tINIT_LIST_HEAD(&inst->queue_list);\n \n-\tspin_lock(&q->instances_lock);\n+\tspin_lock_bh(&q->instances_lock);\n \tif (instance_lookup(q, queue_num)) {\n \t\terr = -EEXIST;\n \t\tgoto out_unlock;\n@@ -204,7 +204,7 @@ instance_create(struct nfnl_queue_net *q, u_int16_t queue_num, u32 portid)\n \th = instance_hashfn(queue_num);\n \thlist_add_head_rcu(&inst->hlist, &q->instance_table[h]);\n \n-\tspin_unlock(&q->instances_lock);\n+\tspin_unlock_bh(&q->instances_lock);\n \n \treturn inst;\n \n","prefixes":[]}