From: Filipe Manana <fdmanana@suse.com> stable inclusion from stable-v5.10.150 commit 47b5ffe86332af95f0f52be0a63d4da7c2b37b55 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6D0XA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 331cd9461412e103d07595a10289de90004ac890 upstream. When enabling quotas, at btrfs_quota_enable(), after committing the transaction, we change fs_info->quota_root to point to the quota root we created and set BTRFS_FS_QUOTA_ENABLED at fs_info->flags. Then we try to start the qgroup rescan worker, first by initializing it with a call to qgroup_rescan_init() - however if that fails we end up freeing the quota root but we leave fs_info->quota_root still pointing to it, this can later result in a use-after-free somewhere else. We have previously set the flags BTRFS_FS_QUOTA_ENABLED and BTRFS_QGROUP_STATUS_FLAG_ON, so we can only fail with -EINPROGRESS at btrfs_quota_enable(), which is possible if someone already called the quota rescan ioctl, and therefore started the rescan worker. So fix this by ignoring an -EINPROGRESS and asserting we can't get any other error. Reported-by: Ye Bin <yebin10@huawei.com> Link: https://lore.kernel.org/linux-btrfs/20220823015931.421355-1-yebin10@huawei.c... CC: stable@vger.kernel.org # 4.19+ Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> --- fs/btrfs/qgroup.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index dc512a86d7c7..38f463e6bfaa 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -1158,6 +1158,21 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info) fs_info->qgroup_rescan_running = true; btrfs_queue_work(fs_info->qgroup_rescan_workers, &fs_info->qgroup_rescan_work); + } else { + /* + * We have set both BTRFS_FS_QUOTA_ENABLED and + * BTRFS_QGROUP_STATUS_FLAG_ON, so we can only fail with + * -EINPROGRESS. That can happen because someone started the + * rescan worker by calling quota rescan ioctl before we + * attempted to initialize the rescan worker. Failure due to + * quotas disabled in the meanwhile is not possible, because + * we are holding a write lock on fs_info->subvol_sem, which + * is also acquired when disabling quotas. + * Ignore such error, and any other error would need to undo + * everything we did in the transaction we just committed. + */ + ASSERT(ret == -EINPROGRESS); + ret = 0; } out_free_path: -- 2.25.1