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 B65032D739C; Sat, 12 Sep 2026 13:44:02 +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=1789220644; cv=none; b=oLSWpws1HOmIY7a5pOvZfhPIgC+22ymwkWTGSXJLY+fEr6abthuSPd5GnqxuliScxTrBkRCIu4gKUX8OiaV2D88dUr7vISOgDxX8ibd8ADvOtKvaitqU0350n+xp6CqzOgdlVIV354DFqnfuqmhFCSI7nnJMve358ofGTam4inA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789220644; c=relaxed/simple; bh=/5gGNefdNBiZ38SFZDrg5sk59rPtJIqDJ304j/50lPo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Zkcvaar7zP3FQ32V2saNxzzwfe/PrAGsTSYAUkbHas83T8+ZbaekPOK1QJkrKFB4ggzeuwjT23/CWUgEdcrznjW6uhOpicbYlR7CM/BpgbWD2Ji+FgaTcV+D3OiqZ9ZudI6YOZaYi5pcI2V7d3drb9Xlhx0/Zv04IFDt+X4smLY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=r1fOOeSj; 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="r1fOOeSj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9FE21F000FF; Sat, 12 Sep 2026 13:44:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789220642; bh=HyZASx6qSHu8lyinlV6BVMi9QI7NqQImojaSJpfqBws=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=r1fOOeSj5U6Hqpeo26oXf9G2xFSq2sybjv5sJG4meW1iI3PqZ/KXa5M9eLOyD9J7t xDtWWjS5UoSfTnGT+SfQEdsPoFF7jYchEJVM+iuO6oqc2r0lEQ7ogQXeiAQgtpTtH8 XFjpfNqDPEQod5eHZNnhYcun9tBzvC+RumNo063w= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Jan=20H=C3=B6ppner?= , Stefan Haberland , Jens Axboe Subject: [PATCH 6.6 0220/1424] s390/dasd: Guard sysfs discipline callbacks against unallocated private data Date: Sat, 12 Sep 2026 08:44:12 +0200 Message-ID: <20260912065612.213602688@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065607.279695368@linuxfoundation.org> References: <20260912065607.279695368@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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stefan Haberland commit 2a1780f9fc2493bd34c418a0be6fc58943afcecf upstream. Several sysfs show/store handlers call a discipline callback that dereferences device->private, either directly or through the DASD_DEFINE_ATTR() macro. During dasd_generic_set_online() the discipline is assigned before check_device() allocates device->private, so an unprivileged read of one of these world-readable attributes in that window dereferences a NULL pointer and panics. Guard the dereference inside each callback that actually touches device->private. Fixes: c729696bcf8b ("s390/dasd: Recognise data for ESE volumes") Cc: stable@vger.kernel.org Reviewed-by: Jan Höppner Signed-off-by: Stefan Haberland Link: https://patch.msgid.link/20260805111612.1285190-4-sth@linux.ibm.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/s390/block/dasd_eckd.c | 40 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 38 insertions(+), 2 deletions(-) --- a/drivers/s390/block/dasd_eckd.c +++ b/drivers/s390/block/dasd_eckd.c @@ -1506,6 +1506,8 @@ static void dasd_eckd_reset_path(struct struct dasd_eckd_private *private = device->private; unsigned long flags; + if (!private) + return; if (!private->fcx_max_data) private->fcx_max_data = get_fcx_max_data(device); spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); @@ -1661,6 +1663,9 @@ static int dasd_eckd_is_ese(struct dasd_ { struct dasd_eckd_private *private = device->private; + if (!private) + return 0; + return private->vsq.vol_info.ese; } @@ -1668,6 +1673,9 @@ static int dasd_eckd_ext_pool_id(struct { struct dasd_eckd_private *private = device->private; + if (!private) + return 0; + return private->vsq.extent_pool_id; } @@ -1681,6 +1689,9 @@ static int dasd_eckd_space_configured(st struct dasd_eckd_private *private = device->private; int rc; + if (!private) + return 0; + rc = dasd_eckd_read_vol_info(device); return rc ? : private->vsq.space_configured; @@ -1695,6 +1706,9 @@ static int dasd_eckd_space_allocated(str struct dasd_eckd_private *private = device->private; int rc; + if (!private) + return 0; + rc = dasd_eckd_read_vol_info(device); return rc ? : private->vsq.space_allocated; @@ -1704,6 +1718,9 @@ static int dasd_eckd_logical_capacity(st { struct dasd_eckd_private *private = device->private; + if (!private) + return 0; + return private->vsq.logical_capacity; } @@ -1846,7 +1863,11 @@ static int dasd_eckd_read_ext_pool_info( static int dasd_eckd_ext_size(struct dasd_device *device) { struct dasd_eckd_private *private = device->private; - struct dasd_ext_pool_sum eps = private->eps; + struct dasd_ext_pool_sum eps; + + if (!private) + return 0; + eps = private->eps; if (!eps.flags.extent_size_valid) return 0; @@ -1862,6 +1883,9 @@ static int dasd_eckd_ext_pool_warn_thrsh { struct dasd_eckd_private *private = device->private; + if (!private) + return 0; + return private->eps.warn_thrshld; } @@ -1869,6 +1893,9 @@ static int dasd_eckd_ext_pool_cap_at_war { struct dasd_eckd_private *private = device->private; + if (!private) + return 0; + return private->eps.flags.capacity_at_warnlevel; } @@ -1879,6 +1906,9 @@ static int dasd_eckd_ext_pool_oos(struct { struct dasd_eckd_private *private = device->private; + if (!private) + return 0; + return private->eps.flags.pool_oos; } @@ -5988,8 +6018,11 @@ static int dasd_eckd_query_host_access(s struct ccw1 *ccw; int rc; + if (!private) + return -ENODEV; + /* not available for HYPER PAV alias devices */ - if (!device->block && private->lcu->pav == HYPER_PAV) + if (!device->block && private->lcu && private->lcu->pav == HYPER_PAV) return -EOPNOTSUPP; /* may not be supported by the storage server */ @@ -6854,6 +6887,9 @@ static int dasd_eckd_hpf_enabled(struct { struct dasd_eckd_private *private = device->private; + if (!private) + return 0; + return private->fcx_max_data ? 1 : 0; }