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 138344C8FE4; Tue, 21 Jul 2026 17:54:37 +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=1784656479; cv=none; b=F+1euaSAFssiq54RzJwUM35QCPYM02/wEQsbgcAfRpyPvKjXyt4gAg6GFr3qr2tC8ZHjcLuE4kUpbw3KFd+bFDc7yGnNEwhTxUN/lLPMxkZk3QorVI4UA1GSHYQwS/NWTVakOP+tSDw+asANfhoOq5bL+ydxfqpEzONknaGRx7M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784656479; c=relaxed/simple; bh=x1Mt+m/Ts0IZ01rKrpbpcL9BK9OOkKLel/8lcQzWnfQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=J3do0Bh8/qAggqk2P8DPyECZQxGrpvoMROlbB7eXCp3qRXI1z5jadmnOsrfsBuuaE0cntKygoLUD5BVCl/WuVVc7zhmOL/ABi6hNXuwn5TaYual3xl7BEibnmegUHFV3ymbqw1fNwQMVICGUiq+ZFoIytWK/Pmuh+8flc3Fsw+4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ha87rJ2J; 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="ha87rJ2J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 550021F000E9; Tue, 21 Jul 2026 17:54:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784656476; bh=QXnY3PkBFEvI1ofTVZmCap0IV1bSQvF3ryQj37RXHns=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ha87rJ2J5BC3Jw9uH7zxwaYQ/R5NMsj9B6bVJ7tGYMcvISM99pD40FWZgoR+dBeQr OwGCp8pwdE2MqWEUf1VjA7/IS1HZBznOzI9TZSzqFk6VszpH/0OSpXWdN7MFTGTtro MrJj4f2wWC2p2ESJ4hxvNclKZpXVoTB+25C5o0pY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sechang Lim , Leon Hwang , Kumar Kartikeya Dwivedi , Sasha Levin Subject: [PATCH 6.18 0375/1611] bpf: Fix NULL pointer dereference in bpf_task_from_vpid() Date: Tue, 21 Jul 2026 17:08:11 +0200 Message-ID: <20260721152523.619027037@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@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: Sechang Lim [ Upstream commit 50dff00615522f3ec03449680ca23beb4cfc549c ] bpf_task_from_vpid() looks up a task in the pid namespace of the current task, via find_task_by_vpid(): find_task_by_vpid(vpid) find_task_by_pid_ns(vpid, task_active_pid_ns(current)) find_pid_ns(nr, ns) -> idr_find(&ns->idr, nr) cgroup_skb programs run in softirq, which may interrupt a task that is itself in do_exit(). Once that task has passed exit_notify() -> release_task() -> __unhash_process(), its thread_pid is cleared, so task_active_pid_ns(current) returns NULL and find_pid_ns() dereferences &NULL->idr: BUG: kernel NULL pointer dereference, address: 0000000000000050 RIP: 0010:idr_find+0x11/0x30 lib/idr.c:176 Call Trace: find_pid_ns kernel/pid.c:370 [inline] find_task_by_pid_ns+0x3b/0xe0 kernel/pid.c:485 bpf_task_from_vpid+0x5b/0x200 kernel/bpf/helpers.c:2916 bpf_prog_run_array_cg+0x17e/0x530 kernel/bpf/cgroup.c:81 __cgroup_bpf_run_filter_skb+0x12b/0x250 kernel/bpf/cgroup.c:1612 sk_filter_trim_cap+0x1dc/0x4c0 net/core/filter.c:148 tcp_v4_rcv+0x18d1/0x2200 net/ipv4/tcp_ipv4.c:2223 do_exit+0xa63/0x1270 kernel/exit.c:1010 get_signal+0x141c/0x1530 kernel/signal.c:3037 Bail out when current has no pid namespace. Fixes: 675c3596ff32 ("bpf: Add bpf_task_from_vpid() kfunc") Signed-off-by: Sechang Lim Acked-by: Leon Hwang Link: https://lore.kernel.org/bpf/20260608050001.2545245-1-rhkrqnwk98@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Sasha Levin --- kernel/bpf/helpers.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index a62cbdf5a3cde5..7357ddc1fc9283 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2672,11 +2672,13 @@ __bpf_kfunc struct task_struct *bpf_task_from_vpid(s32 vpid) { struct task_struct *p; - rcu_read_lock(); + guard(rcu)(); + if (!task_active_pid_ns(current)) + return NULL; + p = find_task_by_vpid(vpid); if (p) p = bpf_task_acquire(p); - rcu_read_unlock(); return p; } -- 2.53.0