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 A83E3538D89; Mon, 31 Aug 2026 13:45:26 +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=1788183929; cv=none; b=jgT7l7OsODPNyglzym5sq3lfFCZKOwAXMcLNJomsu4t93OG5lfxQRmPWAqSR97GnyZHEbdO0w/tDpr1QppSoN6bUiLIHRnWidrF0PQMyzfIixnRXW/y7P3cBW8FO47RO16f6FmJHcsbrvuudFwfCHBkNqgMpTq9zZHw52CYPbVM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183929; c=relaxed/simple; bh=PyPqbCh+IdZgNwdgbKxCiX61bfjQM50JmIuKn8uXSF8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=F6Q5O3kk4lAsPKfCl3kR3UNrCSfFwDBu9sOGqGLLRa6URA9Vn59GymMEZRqxDCx838swKm5skZsIzJT3NSLuyz0csIjAZc5x94R0Qh9oiIgDaBmvKyyjSNw0t/DjXx/34/rsBPSNBMOFL/Xyr7BhHkvf9CHZCrZvFXhglYL5Sjk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1XHfbHNR; 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="1XHfbHNR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0D4D71F00A3F; Mon, 31 Aug 2026 13:45:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788183926; bh=jyMxo76uqe5P7SgWfBE7T/bjKDZpE++i86vDtIMYHBY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=1XHfbHNRYyZR5TO82xthnvrUPmINuHXAlpcYInRMs8e4teNH3ecspVuXM+oKIXZ+r ZYtv/+qC8wrWMS6Rl7oC3wjXGPqfNvsutxS3epN2/ej/+Fj+XiP46bibbtcF1vkoiF kiQku+b+bdDdkJzf2ooLpLCpsJF8tlTWaklWjJ2E= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yinhao Hu , Kaiyan Mei , Dongliang Mu , Jiayuan Chen , Daniel Borkmann , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.18 14/83] bpf: Fix use-after-free in offloaded map/prog info fill Date: Mon, 31 Aug 2026 15:33:50 +0200 Message-ID: <20260831133359.938370990@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260831133359.207714926@linuxfoundation.org> References: <20260831133359.207714926@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiayuan Chen [ Upstream commit a0c584fc18056709c8e047a82a6045d6c209f4ce ] 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 -ENOENT -- 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 Reviewed-by: Dongliang Mu Closes: https://lore.kernel.org/bpf/f0aa3678-79c9-47ae-9e8c-02a3d1df160a@hust.edu.cn/ Signed-off-by: Jiayuan Chen Acked-by: Daniel Borkmann Link: https://lore.kernel.org/r/20260409023733.168050-1-jiayuan.chen@linux.dev Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/offload.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index 42ae8d595c2c2..a9a036547c960 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -445,9 +445,8 @@ 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)); + ns = net ? &net->ns : NULL; } else { args->info->ifindex = 0; ns = NULL; @@ -657,9 +656,8 @@ 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)); + ns = net ? &net->ns : NULL; } else { args->info->ifindex = 0; ns = NULL; -- 2.53.0