From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792774074; b=vC9zd1j6Bkg56pgHBodNG3UTQ4fAkzmqdx9QfuA/HgA2MDgSHkthY1HNDQtG+qrgvk5Z rlOn9AW9aX7i00ktO2W+yuPYMaaKRP5Ni4oIGYyhQlOhBXd84Q54n5BcU352z0/tKkD5s 20h18gTFP2fvgLMueeM7UXAoVnS5MDK1XSHvd8YfWjWBjvOjpNfI1IreiE4/SmcTjo5b8 cV3jxNe/6U4Vf7BNji106PlVoCcnm6wbv2oBNppnG0KhtbHt/f2jsik1t7R41Tjd8QXoE EzFlxxqriwcVH29RYOFAdJ1/fJvebLHpQzOaQ9/78TMZm7FKW3H2FxQyU/sKJAm3gHw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792774074; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=fbahacrd+WDlaJ5geIeozvf4107lXBANxplfMc0F9ig=; b=dI3f9rh2gcFufgeeVboJyT7+9SZxoUdjQGoFsbY5yaPp2waTWjToD8YjJqpIABAjDd9/ hn8MoYI2GUD8NBfqs/TltaHVIPMKlu3hANsE0WLz2XJdsCQpUlVXnOpf5/hrAwHGNeSSN yZZ+s0YawePF+WbHXqIZMwYs4PCTVUReuIOvvTnu0VOiqq604v+M9RslVoxf5+pwy1N53 NJIbn9kjf8+gGdlLnZ2+49XgoZXyLfmzaPEV6znvzX3kYmOIx4ObvTjamdqleZN7afJ1K Zpn8TTVv3bz4Eu09FGB9vzAKGG/FURfeNLIPbeDeIYIvDI36KS/g7ualffb+xK/E3bA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=wKE00uJ4; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7EED6606A31B; Fri, 23 Oct 2026 16:47:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=wKE00uJ4 Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA2811F01825; Fri, 23 Oct 2026 16:47:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792774074; bh=fbahacrd+WDlaJ5geIeozvf4107lXBANxplfMc0F9ig=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=wKE00uJ4vqsiseoVdhMiiQJmyStxRz2uToJlHYYQSVLL4nOJDi/VdqDWPjKV7114V woVrIMCfAQVlG0CMKRbPhWi/y1oPKknP4225Ppj8kaGv2q4l3y0J/puV7zFQUE/M67 E4B39oL0+5lLF+j1KvqDUA8FmAo/9gbTOBOutTuc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko , David Carlier , Steven Rostedt Subject: [PATCH 6.18 095/193] ring-buffer: Do not show buffer_meta for CPUs without a buffer Date: Fri, 23 Oct 2026 18:36:12 +0200 Message-ID: <20261023163716.451505698@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261023163714.201276352@linuxfoundation.org> References: <20261023163714.201276352@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Carlier commit 3f23cae09a4677a3f7c163a68388512cb231ff22 upstream. The per_cpu/cpuN/buffer_meta files are created for every possible CPU, but buffer->buffers[cpu] is only allocated once that CPU comes online. Reading the file of a CPU that never came online dereferences a NULL cpu_buffer in rbm_start(). Fail the open with -ENODEV when the CPU has no buffer, as the other per CPU ring buffer interfaces do. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260914133506.4865-3-devnexen@gmail.com Fixes: 950032ffcee7 ("ring-buffer: Add output of ring buffer meta page") Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260913134906.6E8A01F000FF@smtp.kernel.org/ Signed-off-by: David Carlier Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/trace/ring_buffer.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2293,6 +2293,9 @@ int ring_buffer_meta_seq_init(struct fil struct seq_file *m; int ret; + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return -ENODEV; + ret = seq_open(file, &rb_meta_seq_ops); if (ret) return ret;