From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender-op-o17.zoho.eu (sender-op-o17.zoho.eu [136.143.169.17]) (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 B36F735E95E; Fri, 17 Jul 2026 10:58:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.169.17 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784285940; cv=pass; b=gclLHWG4Cc+dJhy+CbcB4GV9xlSk0Pj4GqIOGsa7+c4woX1ezxHqudURV0lx4aBBfSrTjZfuMFaHNp5HMjQQJqxfcQEpWCY67ubk/BkIKyZZlT/ANFr7CiRQ4Iem3L3ZfcD8tSD8hYRo0f4BZ3Di3ssJoPoFmx3kiKh+bB/7E4I= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784285940; c=relaxed/simple; bh=8u0whOsd+mmn1SMUmzQ5shT1J8XMawKQK2hsBsDrBwE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uQXpArxxFwnUyURIxkKSidsEV1Jgo4YKG1LS0hHxeV8jdDRTqEDV5ofvlbvdlWRZrtJ8+7BMD8vIG1Wx+YNzWZU1tvYSqmI3t8AX3/kUIgHEYiJ7UEzywJksFhhfZ3X/rX/V8q5q3scRWozjSH8TD2dY7hV1A5Qk3Ej9LL+W/ow= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=auditcode.ai; spf=pass smtp.mailfrom=auditcode.ai; dkim=pass (1024-bit key) header.d=auditcode.ai header.i=security@auditcode.ai header.b=LGQtjftx; arc=pass smtp.client-ip=136.143.169.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=auditcode.ai Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=auditcode.ai Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=auditcode.ai header.i=security@auditcode.ai header.b="LGQtjftx" ARC-Seal: i=1; a=rsa-sha256; t=1784285897; cv=none; d=zohomail.eu; s=zohoarc; b=EAckR6cqY7bIkEmftKPTAdk/2viGjnM3kMd2TKoUbiYz6PLQbsigAkzhBi4J/stQZdZ/fQ5eGrNbBaLTA2H26Y8rbylEQGBBsUfeiFy7dgpZHn3CpMxm+Kd+IpZUqWuV2uVA6OqItrxo7KQjg6bfriD+qqZfQhnuUhXTvf17MEc= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.eu; s=zohoarc; t=1784285897; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To; bh=bg1KaixGUzd1fGg12IcFm179oJF5oYZKPHKuj76fMuk=; b=Yy1fhaALace5hnB+YGI3mJjOoutiDP/9beuVGMkPduPf5k2hwvcxuJePn3QNGw3fcL9qdcQD9lU1LFyJ3zc4JZv7eegeeDArNvtIDNxJeuE/MCeR0OaOGAVWiIoxgPqsYOBM09P/98322rRjdtLIYGkX3cvBK6q1lobqS7IEVd8= ARC-Authentication-Results: i=1; mx.zohomail.eu; dkim=pass header.i=auditcode.ai; spf=pass smtp.mailfrom=security@auditcode.ai; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1784285897; s=zmail; d=auditcode.ai; i=security@auditcode.ai; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:In-Reply-To:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=bg1KaixGUzd1fGg12IcFm179oJF5oYZKPHKuj76fMuk=; b=LGQtjftxoTRJrIvF48Rizd6Oo2QIfIvEkatmmeB9NvCFQ+e3ihigXcJM0eqyijFR SEeFzdxqo4wW0whdi3umE6XYaPMyEBSTLxn1aySDKeZEWjNe+Ri9C9Wa8mGgm6nixOr Gwy1Q/2mnv8qDx4FkZv6tCOT+ZgCcnMk+E4rU/qc= Received: by mx.zoho.eu with SMTPS id 1784285893972518.5676848574119; Fri, 17 Jul 2026 12:58:13 +0200 (CEST) From: Ibrahim Hashimov To: alex.aring@gmail.com, miquel.raynal@bootlin.com, stefan@datenfreihafen.org Cc: linux-wpan@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v2] mac802154: hold an interface reference across the scan worker Date: Fri, 17 Jul 2026 12:58:09 +0200 Message-ID: <20260717105810.26226-1-security@auditcode.ai> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260710140927.13228-1-security@auditcode.ai> References: <20260710140927.13228-1-security@auditcode.ai> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-ZohoMailClient: External mac802154_scan_worker() captures the scanning sub-interface once under RCU: sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(scan_req->wpan_dev); and then, after rcu_read_unlock() and outside the rtnl, keeps dereferencing sdata->dev: in the channel-change and restart failure traces, in mac802154_transmit_beacon_req() (skb->dev = sdata->dev) for active scans, in the final dev_dbg(), and in the end_scan mac802154_scan_cleanup_locked() path. Nothing keeps that netdev alive for the duration of the worker iteration. A concurrent teardown of the scanning interface -- userspace issuing NL802154_CMD_DEL_INTERFACE (ieee802154_if_remove() -> unregister_netdevice()), or a full PHY removal via ieee802154_unregister_hw() -> ieee802154_remove_interfaces() -- can run as soon as the worker drops the rtnl between its two short drv_set_channel()/drv_start() sections. The netdev is not freed synchronously by unregister_netdevice(): it is queued to net_todo_list and freed later from netdev_run_todo(), which drops the rtnl mutex (__rtnl_unlock()) *before* netdev_wait_allrefs_any()/free_netdev(). The freeing therefore runs with the rtnl not held, on whichever task next drains net_todo_list. Holding the rtnl in the worker does not prevent it, and the per-PHY IEEE802154_IS_SCANNING flag does not identify the specific interface: a subsequent NEW_INTERFACE + TRIGGER_SCAN re-arms the flag, so a stale worker iteration sails past an is-scanning recheck and dereferences the already-freed netdev. Triggering the race requires CAP_NET_ADMIN: both NL802154_CMD_TRIGGER_SCAN and NL802154_CMD_DEL_INTERFACE are GENL_ADMIN_PERM, reachable only from the initial user namespace, so the attacker is a locally privileged (CAP_NET_ADMIN) user, not an unprivileged local user or a remote peer. KASAN slab-use-after-free, kworker reading the freed net_device/ieee802154_sub_if_data (kmalloc-cg-4k) allocated and freed by the racing NEW_INTERFACE/DEL_INTERFACE task: BUG: KASAN: slab-use-after-free in mac802154_scan_worker+0x... [mac802154] Read of size 8 ... by task kworker/u8:N Workqueue: phy0-mac-cmds mac802154_scan_worker [mac802154] mac802154_scan_worker process_one_work Fix it by taking a reference on the interface while the RCU read lock is still held -- so the netdev cannot be freed before the refcount is raised -- and releasing it at every exit of the worker past that point. This keeps sdata->dev valid for the whole iteration. The reference does not defer the free indefinitely: a teardown started while it is held simply blocks in netdev_run_todo() until the current iteration returns, and it cannot self-deadlock the single-threaded mac_wq because the unregistering task claims the net_todo_list entry under the rtnl, so the blocking netdev_wait_allrefs_any() always runs on that task, not on the worker. Verified on a v6.19 KASAN build: racing DEL_INTERFACE against an in-flight TRIGGER_SCAN reliably tripped a slab-use-after-free KASAN report inside mac802154_scan_worker() before this patch, and the same reproducer no longer triggers it with the fix applied. Fixes: 57588c71177f ("mac802154: Handle passive scanning") Cc: stable@vger.kernel.org Signed-off-by: Ibrahim Hashimov Assisted-by: AuditCode-AI:2026.07 --- v2: trim the in-worker comment down to the essentials, as requested by Miquel Raynal. No functional change. net/mac802154/scan.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c index 300d4584533e..5b4ea2a895cc 100644 --- a/net/mac802154/scan.c +++ b/net/mac802154/scan.c @@ -209,6 +209,14 @@ void mac802154_scan_worker(struct work_struct *work) return; } + /* + * sdata->dev is dereferenced below after rcu_read_unlock() and outside + * the rtnl, and a concurrent DEL_INTERFACE / PHY teardown can free it + * asynchronously from netdev_run_todo(). Pin it with a reference taken + * while the RCU read lock is still held, and drop it at every exit. + */ + dev_hold(sdata->dev); + wpan_phy = scan_req->wpan_phy; scan_req_type = scan_req->type; scan_req_duration = scan_req->duration; @@ -262,12 +270,14 @@ void mac802154_scan_worker(struct work_struct *work) "Scan page %u channel %u for %ums\n", page, channel, jiffies_to_msecs(scan_duration)); queue_delayed_work(local->mac_wq, &local->scan_work, scan_duration); + dev_put(sdata->dev); return; end_scan: rtnl_lock(); mac802154_scan_cleanup_locked(local, sdata, false); rtnl_unlock(); + dev_put(sdata->dev); } int mac802154_trigger_scan_locked(struct ieee802154_sub_if_data *sdata, -- 2.50.1 (Apple Git-155)