From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta1.migadu.com (out-177.mta1.migadu.com [95.215.58.177]) (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 42DB63B8928 for ; Wed, 8 Apr 2026 10:49:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775645346; cv=none; b=ALNe5jIPhbR/sqRXt/1ZrblHriNI1KF6mJr0ii5HvDqXbidW/3annVvI9utUGMdIx5HXznYy2JcLTjZJNkfSdWncaGjS7XaxIu/dTeqhT3YkANzUrfjAm3IoBZLZt5/V8NnRQlGr/3a+u7u0eOmroxdjMNwGq5Cr1/Sm4rAAEhE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775645346; c=relaxed/simple; bh=qDfq7B1jAeoui31LJGm9SGD8izpu3YkVBn8qweM8r+0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=jCNtuUYcqi9sR59HnjkqCQHJzEN3rNkqBrdrJMrcXUyQbtVcIsAsbOfV6j3PVpDN8bI965EmEzegTYDExNHo+yWldtDXK0aP/E1On+ynp0am5KYbes2nYif59uka/PQg0d+CCrEjIhotfwuHyfMVGQtDblhOXp8DfQfUG6zcQxo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=dxUlZM2x; arc=none smtp.client-ip=95.215.58.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="dxUlZM2x" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1775645342; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=h++aYznlUjGCsdITk5Sm0RChqsDmheECuw/vR5Kr2yM=; b=dxUlZM2xnldQnlYl4N5jRzSOR/4iEQPX5MPVa1HLHWMiRUmDXxXjzGtfZR14F5xzxd4Kp1 6veeT9stLPx8GCjAI0bRhzJId6qiU8ooqsSv/BQ+C3MSAJWowrg32hq0KE6u3wbzEn4U1k jGBxHryn/JLvR+tLm0Y9mBp+6O9BVBQ= From: Jiayuan Chen To: bpf@vger.kernel.org Cc: Jiayuan Chen , Yinhao Hu , Kaiyan Mei , Dongliang Mu , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , Jakub Kicinski , linux-kernel@vger.kernel.org Subject: [PATCH bpf] bpf: Fix use-after-free in offloaded map/prog info fill Date: Wed, 8 Apr 2026 18:47:31 +0800 Message-ID: <20260408104732.259683-1-jiayuan.chen@linux.dev> 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-Migadu-Flow: FLOW_OUT When querying info for an offloaded BPF map or program, bpf_map_offload_info_fill_ns() and bpf_prog_offload_info_fill_ns() obtain the network namespace with get_net(dev_net(offmap->netdev)). However, the associated netdev's netns may be racing with teardown during netns destruction. If the netns refcount has already reached 0, get_net() performs a refcount_t increment on 0, triggering: refcount_t: addition on 0; use-after-free. Although rtnl_lock and bpf_devs_lock ensure the netdev pointer remains valid, they cannot prevent the netns refcount from reaching zero. Fix this by using maybe_get_net() instead of get_net(). maybe_get_net() uses refcount_inc_not_zero() and returns NULL if the refcount is already zero, which causes ns_get_path_cb() to fail and the caller to return -ENODEV -- the correct behavior when the netns is being destroyed. Fixes: 675fc275a3a2d ("bpf: offload: report device information for offloaded programs") Fixes: 52775b33bb507 ("bpf: offload: report device information about offloaded maps") Reported-by: Yinhao Hu Reported-by: Kaiyan Mei Reported-by: Dongliang Mu Closes: https://lore.kernel.org/bpf/f0aa3678-79c9-47ae-9e8c-02a3d1df160a@hust.edu.cn/ Signed-off-by: Jiayuan Chen --- kernel/bpf/offload.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index 0ad97d643bf49..d6dc684d0e872 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -435,9 +435,12 @@ static struct ns_common *bpf_prog_offload_info_fill_ns(void *private_data) if (aux->offload) { args->info->ifindex = aux->offload->netdev->ifindex; - net = dev_net(aux->offload->netdev); - get_net(net); - ns = &net->ns; + net = maybe_get_net(dev_net(aux->offload->netdev)); + if (net) { + ns = &net->ns; + } else { + ns = NULL; + } } else { args->info->ifindex = 0; ns = NULL; @@ -647,9 +650,12 @@ static struct ns_common *bpf_map_offload_info_fill_ns(void *private_data) if (args->offmap->netdev) { args->info->ifindex = args->offmap->netdev->ifindex; - net = dev_net(args->offmap->netdev); - get_net(net); - ns = &net->ns; + net = maybe_get_net(dev_net(args->offmap->netdev)); + if (net) { + ns = &net->ns; + } else { + ns = NULL; + } } else { args->info->ifindex = 0; ns = NULL; -- 2.43.0