From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 067C434EEE4; Tue, 16 Dec 2025 11:46:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765885613; cv=none; b=juHKOM+D3Wp2hICi+tQaBQo+E12onAd0X84NqNRlj0Zve3lANriytwvk3YGn/5fnLNYeXmU0OHIgWyl3Kcng6wy6bspCyHZO91XWkWa7yHVNfenipVxoLa8rM98/7CErWm5KMNwr89zvSlPNSteSCzmZN7osnzvZI16oaCwCZPU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765885613; c=relaxed/simple; bh=yHk4urGp57CrnGj1viNWXTazc4tlcjVvW8IguAJNcDw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nzWGKSyBuZ/f75sr/zFop9KQXjsdVKSdE+mBlt6ocN0V1TxbrgDtn8G47X2mlCeZXHHNJ8WWs7C9U4EUuGhqe0HjNi+LUytMtzH52IlhxKjrkXDVAwFRMHVlssCgchQ+U3pBzTVyD//5q11+eJj2+AOLo3gHgBYx/47IbNtEftA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=a6FeNJVw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="a6FeNJVw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5004CC4CEF1; Tue, 16 Dec 2025 11:46:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1765885612; bh=yHk4urGp57CrnGj1viNWXTazc4tlcjVvW8IguAJNcDw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a6FeNJVwJC63XvqvSXulKfl0bkEZhgl+RdiGSnCF+FJP+vrsCSGk9hmd7FteHmZ2G QAtAssO54i528lgE7VQdFxl2U/tGwojZhRjxEN7ay6u6h12SaxmKN5cVCnRChJEgAh eBd6uTSQKVB2mvRVJ8V36GHaLD0oxiwrg3FsVS/Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yun Zhou , Li Nan , Yu Kuai , Sasha Levin Subject: [PATCH 6.17 191/507] md: fix rcu protection in md_wakeup_thread Date: Tue, 16 Dec 2025 12:10:32 +0100 Message-ID: <20251216111352.431484952@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251216111345.522190956@linuxfoundation.org> References: <20251216111345.522190956@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 6.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yun Zhou [ Upstream commit 0dc76205549b4c25705e54345f211b9f66e018a0 ] We attempted to use RCU to protect the pointer 'thread', but directly passed the value when calling md_wakeup_thread(). This means that the RCU pointer has been acquired before rcu_read_lock(), which renders rcu_read_lock() ineffective and could lead to a use-after-free. Link: https://lore.kernel.org/linux-raid/20251015083227.1079009-1-yun.zhou@windriver.com Fixes: 446931543982 ("md: protect md_thread with rcu") Signed-off-by: Yun Zhou Reviewed-by: Li Nan Reviewed-by: Yu Kuai Signed-off-by: Yu Kuai Signed-off-by: Sasha Levin --- drivers/md/md.c | 14 ++++++-------- drivers/md/md.h | 8 +++++++- 2 files changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 07e48faa87e0b..436aab6c5d3de 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -100,7 +100,7 @@ static int remove_and_add_spares(struct mddev *mddev, struct md_rdev *this); static void mddev_detach(struct mddev *mddev); static void export_rdev(struct md_rdev *rdev, struct mddev *mddev); -static void md_wakeup_thread_directly(struct md_thread __rcu *thread); +static void md_wakeup_thread_directly(struct md_thread __rcu **thread); /* * Default number of read corrections we'll attempt on an rdev @@ -4984,7 +4984,7 @@ static void stop_sync_thread(struct mddev *mddev, bool locked) * Thread might be blocked waiting for metadata update which will now * never happen */ - md_wakeup_thread_directly(mddev->sync_thread); + md_wakeup_thread_directly(&mddev->sync_thread); if (work_pending(&mddev->sync_work)) flush_work(&mddev->sync_work); @@ -8196,22 +8196,21 @@ static int md_thread(void *arg) return 0; } -static void md_wakeup_thread_directly(struct md_thread __rcu *thread) +static void md_wakeup_thread_directly(struct md_thread __rcu **thread) { struct md_thread *t; rcu_read_lock(); - t = rcu_dereference(thread); + t = rcu_dereference(*thread); if (t) wake_up_process(t->tsk); rcu_read_unlock(); } -void md_wakeup_thread(struct md_thread __rcu *thread) +void __md_wakeup_thread(struct md_thread __rcu *thread) { struct md_thread *t; - rcu_read_lock(); t = rcu_dereference(thread); if (t) { pr_debug("md: waking up MD thread %s.\n", t->tsk->comm); @@ -8219,9 +8218,8 @@ void md_wakeup_thread(struct md_thread __rcu *thread) if (wq_has_sleeper(&t->wqueue)) wake_up(&t->wqueue); } - rcu_read_unlock(); } -EXPORT_SYMBOL(md_wakeup_thread); +EXPORT_SYMBOL(__md_wakeup_thread); struct md_thread *md_register_thread(void (*run) (struct md_thread *), struct mddev *mddev, const char *name) diff --git a/drivers/md/md.h b/drivers/md/md.h index 51af29a030793..c989cc9f6216b 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -878,6 +878,12 @@ struct md_io_clone { #define THREAD_WAKEUP 0 +#define md_wakeup_thread(thread) do { \ + rcu_read_lock(); \ + __md_wakeup_thread(thread); \ + rcu_read_unlock(); \ +} while (0) + static inline void safe_put_page(struct page *p) { if (p) put_page(p); @@ -891,7 +897,7 @@ extern struct md_thread *md_register_thread( struct mddev *mddev, const char *name); extern void md_unregister_thread(struct mddev *mddev, struct md_thread __rcu **threadp); -extern void md_wakeup_thread(struct md_thread __rcu *thread); +extern void __md_wakeup_thread(struct md_thread __rcu *thread); extern void md_check_recovery(struct mddev *mddev); extern void md_reap_sync_thread(struct mddev *mddev); extern enum sync_action md_sync_action(struct mddev *mddev); -- 2.51.0