diff options
| author | Christoph Hellwig <hch@lst.de> | 2021-08-16 14:26:14 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-08-16 10:49:11 -0600 |
| commit | 889c05cc5834a1eef2dbe1e639cfd7a81c4f4c6d (patch) | |
| tree | 61d680894772d993d79976efa1c593cfdb1c0dff | |
| parent | 9451aa0aacaf7ea13d1acfd5de8b63a6e0b24fac (diff) | |
block: ensure the bdi is freed after inode_detach_wb
inode_detach_wb references the "main" bdi of the inode. With the
recent change to move the bdi from the request_queue to the gendisk
this causes a guaranteed use after free when using certain cgroup
configurations. The big itself is older through as any non-default
inode reference (e.g. an open file descriptor) could have injected
this use after free even before that.
Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks")
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Reported-by: syzbot <syzbot+1fb38bb7d3ce0fa3e1c4@syzkaller.appspotmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210816122614.601358-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/genhd.c | 1 | ||||
| -rw-r--r-- | fs/block_dev.c | 7 |
2 files changed, 4 insertions, 4 deletions
diff --git a/block/genhd.c b/block/genhd.c index ed58ddf6258b..731a46063132 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1084,7 +1084,6 @@ static void disk_release(struct device *dev) might_sleep(); - bdi_put(disk->bdi); disk_release_events(disk); kfree(disk->random); xa_destroy(&disk->part_tbl); diff --git a/fs/block_dev.c b/fs/block_dev.c index 4bd2a632c79c..d3a8062302a0 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -812,8 +812,11 @@ static void bdev_free_inode(struct inode *inode) free_percpu(bdev->bd_stats); kfree(bdev->bd_meta_info); - if (!bdev_is_partition(bdev)) + if (!bdev_is_partition(bdev)) { + if (bdev->bd_disk && bdev->bd_disk->bdi) + bdi_put(bdev->bd_disk->bdi); kfree(bdev->bd_disk); + } if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR) blk_free_ext_minor(MINOR(bdev->bd_dev)); @@ -833,8 +836,6 @@ static void bdev_evict_inode(struct inode *inode) truncate_inode_pages_final(&inode->i_data); invalidate_inode_buffers(inode); /* is it needed here? */ clear_inode(inode); - /* Detach inode from wb early as bdi_put() may free bdi->wb */ - inode_detach_wb(inode); } static const struct super_operations bdev_sops = { |