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 33F273793CA; Sat, 12 Sep 2026 18:54:57 +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=1789239298; cv=none; b=j4HDmEKHR91JqHa68m8StdCbpIROi/DexFDHeL8FfZGIQAg2Cdh7723glpbrVFWm+9C4OCz7I6aD7bSTYpEDMZQ4XHEZ6dX9hJUdpqV2pi5/t/mUP733qjAooAa6vPITn4xEPAU2WcaD489oICC0jwrWAfsVkAmULFSVpUB8SqE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789239298; c=relaxed/simple; bh=V8bpkmbtkozULSPxu/Mf+arJBHfjAiT3txBuBbRfgVs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aFwBSHIWK8L6mcLPv3LgTKFOW1llzbHm9YWzfKP80BwCgkFE1YkxewXVZ+3JHAYAjYnaz7tSvv9N42pGFy7njsgHJlNQTtKT3PIS+Txa+HjfmqfiMUVvjy7st283UiEnwUYdU0KRyXFNs8J4TIJE/8OG/JGOU4QJVhLC0+xH5jw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EC8/kpK+; 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="EC8/kpK+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A7521F000FF; Sat, 12 Sep 2026 18:54:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789239297; bh=sWnfPurvDKgo4/OYnCPXA18H334UEKEdgc10JPL/1pA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EC8/kpK+GhIkQlRw06bzeW47l+/uKoYfKIZHRuUn2RgLBjiEP0f/WI+hvTczctVwZ Pxp1EMKx8XHg6BYcLx6b+5a77TGIHaMT5EWptaeA+3Xp7MZF8XLW7mF/t3ijmHe4mZ Ub5vxDn2e/iz+6vR7DN4TPXVf47fTPgukVDwTkvI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , Pu Lehui , Andrii Nakryiko , Amery Hung , Emil Tsalapatis , Sasha Levin Subject: [PATCH 5.15 637/935] bpf: Fix potential UAF in bpf_netns_link_update_prog Date: Sat, 12 Sep 2026 09:01:07 +0200 Message-ID: <20260912065541.448649021@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pu Lehui [ Upstream commit 5c5997836381010fc5907b36bc17d3b19407e933 ] In bpf_netns_link_update_prog, the checks for old_prog and prog type are currently performed locklessly before acquiring netns_bpf_mutex. This creates a race condition that can lead to a UAF issue. If two threads concurrently execute BPF_LINK_UPDATE on the same netns link, the following execution path can trigger a UAF: CPU0 CPU1 bpf_netns_link_update_prog if (old_prog && old_prog != link->prog) return -EPERM; bpf_netns_link_update_prog if (old_prog && old_prog != link->prog) ... old_prog = xchg(&link->prog, new_prog); bpf_prog_put(old_prog); if (new_prog->type != link->prog->type) <-- trigger UAF Fix this by moving the old_prog and prog->type checks inside the netns_bpf_mutex critical section. Meanwhile, use guard() to simplify lock management and avoid all the goto jumping. Fixes: 7f045a49fee0 ("bpf: Add link-based BPF program attachment to network namespace") Reported-by: Sashiko Signed-off-by: Pu Lehui Signed-off-by: Andrii Nakryiko Reviewed-by: Amery Hung Reviewed-by: Emil Tsalapatis Link: https://lore.kernel.org/bpf/f87b53c0-8f00-45a6-82db-8242fa9b143f@huaweicloud.com [0] Link: https://lore.kernel.org/bpf/20260728023259.2813482-1-pulehui@huaweicloud.com Signed-off-by: Sasha Levin --- kernel/bpf/net_namespace.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c index 542f275bf2523..ad19cb4008e7c 100644 --- a/kernel/bpf/net_namespace.c +++ b/kernel/bpf/net_namespace.c @@ -171,33 +171,28 @@ static int bpf_netns_link_update_prog(struct bpf_link *link, struct net *net; int idx, ret; + guard(mutex)(&netns_bpf_mutex); + if (old_prog && old_prog != link->prog) return -EPERM; if (new_prog->type != link->prog->type) return -EINVAL; - mutex_lock(&netns_bpf_mutex); - net = net_link->net; - if (!net || !check_net(net)) { + if (!net || !check_net(net)) /* Link auto-detached or netns dying */ - ret = -ENOLINK; - goto out_unlock; - } + return -ENOLINK; run_array = rcu_dereference_protected(net->bpf.run_array[type], lockdep_is_held(&netns_bpf_mutex)); idx = link_index(net, type, net_link); ret = bpf_prog_array_update_at(run_array, idx, new_prog); if (ret) - goto out_unlock; + return ret; old_prog = xchg(&link->prog, new_prog); bpf_prog_put(old_prog); - -out_unlock: - mutex_unlock(&netns_bpf_mutex); - return ret; + return 0; } static int bpf_netns_link_fill_info(const struct bpf_link *link, -- 2.53.0