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[144.49.247.101]) by smtp-relay.gmail.com with ESMTPS id 46e09a7af769-7eb54433d7bsm727984a34.5.2026.07.03.04.24.39 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 Jul 2026 04:24:39 -0700 (PDT) X-Relaying-Domain: broadcom.com X-CFilter-Loop: Reflected Received: by mail-qk1-f199.google.com with SMTP id af79cd13be357-92e538afe65so48556685a.3 for ; Fri, 03 Jul 2026 04:24:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; t=1783077879; x=1783682679; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=TmNFWGnLyAB8YGdW9Dzd3teB761dU5G/TuuiXhJ4Ikc=; b=NlP8WBuNnlF2e+yHmu+4WsBg+KnRzUcaQBFzMt8m8v/Le2KxkGnSFX/EfOtCdPfFME dWqIn3XLi2gcZE70D/hNxTUhR6rCva7nzEjsjDPuD5HWtDJzUymVzKuT6vojqZdUnaQQ hWMhyXaaXDz7WrydWwMvEWX93b1Nl2URiH0qU= X-Forwarded-Encrypted: i=1; AFNElJ/pLp8bd+Idds7nfNjBCdMaf9yGuIX3jTvWAC2wWDEZM6snJf/rPbYHP4l9n5d4Ges5dHGJtYEKpUuMGbM=@vger.kernel.org X-Received: by 2002:a05:620a:4892:b0:92b:67e6:8ab2 with SMTP id af79cd13be357-92e7850600cmr1377207585a.60.1783077878956; Fri, 03 Jul 2026 04:24:38 -0700 (PDT) X-Received: by 2002:a05:620a:4892:b0:92b:67e6:8ab2 with SMTP id af79cd13be357-92e7850600cmr1377203285a.60.1783077878469; Fri, 03 Jul 2026 04:24:38 -0700 (PDT) Received: from lvnvda4076.lvn.broadcom.net ([192.19.161.250]) by smtp.gmail.com with ESMTPSA id af79cd13be357-92e90cfdefasm138100285a.47.2026.07.03.04.24.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Jul 2026 04:24:37 -0700 (PDT) From: Kiran Kella To: daniel.zahka@gmail.com, kuba@kernel.org, willemdebruijn.kernel@gmail.com Cc: davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, horms@kernel.org, weibunny@fb.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jayakrishnan.udayavarma@broadcom.com, ajit.khaparde@broadcom.com, akhilesh.samineni@broadcom.com, Kiran Kella , Vikas Gupta , Bhargava Marreddy Subject: [PATCH net] psp: fix NULL genl_sock deref race with concurrent netns teardown Date: Fri, 3 Jul 2026 04:24:31 -0700 Message-ID: <20260703112431.2860506-1-kiran.kella@broadcom.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-DetectorID-Processed: b00c1d49-9d2e-4205-b15f-d015386d3d5e The race occurs between network namespace removal and PSP device unregistration. When a netns is deleted while a PSP device associated with that netns is concurrently being removed, psp_dev_unregister() triggers psp_nl_notify_dev() to send a device change notification. Concurrently, cleanup_net() running in the netns workqueue calls genl_pernet_exit(), which sets net->genl_sock to NULL. If genl_pernet_exit() wins the race, two sites in psp_nl_multicast_per_ns() then dereference the NULL socket and crash: CPU 0 (netns teardown) CPU 1 (PSP device unregister) ====================== ============================= cleanup_net [workqueue] genl_pernet_exit() psp_dev_unregister() net->genl_sock = NULL psp_nl_notify_dev() psp_nl_multicast_per_ns() build_ntf() -> netlink_has_listeners(NULL) /* crash */ genlmsg_multicast_netns() -> nlmsg_multicast_filtered(NULL) /* crash */ Both the main_net path (derived from psd->main_netdev) and each assoc_net entry in psd->assoc_dev_list are affected. Fix by replacing the bare dev_net() calls with maybe_get_net(). maybe_get_net() returns NULL if the namespace is already dying. Holding the reference ensures genl_sock remains valid across both the build_ntf() and genlmsg_multicast_netns() calls. Fixes: 00c94ca2b99e ("psp: base PSP device support") Fixes: 06c2dce2d0f6 ("psp: add new netlink cmd for dev-assoc and dev-disassoc") Signed-off-by: Kiran Kella Reviewed-by: Ajit Khaparde Reviewed-by: Vikas Gupta Reviewed-by: Bhargava Marreddy --- net/psp/psp_nl.c | 33 +++++++++++++++++++++------------ 1 file changed, 21 insertions(+), 12 deletions(-) diff --git a/net/psp/psp_nl.c b/net/psp/psp_nl.c index 9610d8c456ff..24ab626a9e8a 100644 --- a/net/psp/psp_nl.c +++ b/net/psp/psp_nl.c @@ -62,36 +62,45 @@ psp_nl_multicast_per_ns(struct psp_dev *psd, unsigned int group, struct net *main_net; struct sk_buff *ntf; - main_net = dev_net(psd->main_netdev); + main_net = maybe_get_net(dev_net(psd->main_netdev)); + if (!main_net) + return; + xa_init(&sent_nets); list_for_each_entry(entry, &psd->assoc_dev_list, dev_list) { struct net *assoc_net = dev_net(entry->assoc_dev); + struct net *net; int ret; if (net_eq(assoc_net, main_net)) continue; - ret = xa_insert(&sent_nets, (unsigned long)assoc_net, assoc_net, - GFP_KERNEL); - if (ret == -EBUSY) + net = maybe_get_net(assoc_net); + if (!net) continue; - ntf = build_ntf(psd, assoc_net, ctx); - if (!ntf) + ret = xa_insert(&sent_nets, (unsigned long)assoc_net, assoc_net, + GFP_KERNEL); + if (ret == -EBUSY) { + put_net(net); continue; + } - genlmsg_multicast_netns(&psp_nl_family, assoc_net, ntf, 0, - group, GFP_KERNEL); + ntf = build_ntf(psd, net, ctx); + if (ntf) + genlmsg_multicast_netns(&psp_nl_family, net, ntf, 0, + group, GFP_KERNEL); + put_net(net); } xa_destroy(&sent_nets); /* Send to main device netns */ ntf = build_ntf(psd, main_net, ctx); - if (!ntf) - return; - genlmsg_multicast_netns(&psp_nl_family, main_net, ntf, 0, group, - GFP_KERNEL); + if (ntf) + genlmsg_multicast_netns(&psp_nl_family, main_net, ntf, 0, group, + GFP_KERNEL); + put_net(main_net); } static struct sk_buff *psp_nl_clone_ntf(struct psp_dev *psd, struct net *net, -- 2.54.0