From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: [PATCH v4 0/2] blk-cgroup: Fix potential UAF & flush rstat at blkgs destruction path Date: Wed, 14 Dec 2022 22:31:30 -0500 Message-ID: <20221215033132.230023-1-longman@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1671075117; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=veCyvm43EvJLg9G9hhu4AmM7THRxqVqHEQtr8ufuCSo=; b=iJoJqwZ+7thbe+rwo3QNBWbueHh9VCFIGkejROPzRkVSbsPAojqqecLxoH6F6mSEZzjqXr TxeFq9SpJQnlbIYxgBQczKUi9MpqTKxuLiLK4Hab5L4Egukt+WXlLHkq8m4n9XuB4vAhK2 wgm9OY5q3R2ztYNeHN1nLVTdSQKjk1c= List-ID: Content-Type: text/plain; charset="us-ascii" To: Jens Axboe , Tejun Heo , Josef Bacik , Zefan Li , Johannes Weiner , Andrew Morton Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, =?UTF-8?q?Michal=20Koutn=C3=BD?= , "Dennis Zhou (Facebook)" , Waiman Long v4: - Update comment and commit logs for both patches. v3: - Drop v2 patch 2 as it may not be needed. - Replace css_tryget() with percpu_ref_is_zero() in patch 1 as suggested by Tejun. - Expand comment on patch 2 to elaborate the reason for this patch. v2: - Remove unnecessary rcu_read_{lock|unlock} from cgroup_rstat_css_cpu_flush() in patch 3. It was found that blkcg_destroy_blkgs() may be called with all blkcg references gone. This may potentially cause user-after-free and so should be fixed. The second patch flushes rstat when calling blkcg_destroy_blkgs(). Waiman Long (2): bdi, blk-cgroup: Fix potential UAF of blkcg blk-cgroup: Flush stats at blkgs destruction path block/blk-cgroup.c | 23 +++++++++++++++++++++++ include/linux/cgroup.h | 1 + kernel/cgroup/rstat.c | 18 ++++++++++++++++++ mm/backing-dev.c | 8 ++++++-- 4 files changed, 48 insertions(+), 2 deletions(-) -- 2.31.1