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| author | Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> | 2021-10-02 18:23:02 +0900 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-10-02 07:29:20 -0600 |
| commit | 06cc978d3ff226072780f74897800b33e78abb57 (patch) | |
| tree | f8a7767f98974d2bea074848be82708931e5795a /block | |
| parent | 41e76c6a3c83c85e849f10754b8632ea763d9be4 (diff) | |
| download | lwn-06cc978d3ff226072780f74897800b33e78abb57.tar.gz lwn-06cc978d3ff226072780f74897800b33e78abb57.zip | |
block: genhd: fix double kfree() in __alloc_disk_node()
syzbot is reporting use-after-free read at bdev_free_inode() [1], for
kfree() from __alloc_disk_node() is called before bdev_free_inode()
(which is called after RCU grace period) reads bdev->bd_disk and calls
kfree(bdev->bd_disk).
Fix use-after-free read followed by double kfree() problem
by making sure that bdev->bd_disk is NULL when calling iput().
Link: https://syzkaller.appspot.com/bug?extid=8281086e8a6fbfbd952a [1]
Reported-by: syzbot <syzbot+8281086e8a6fbfbd952a@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/e6dd13c5-8db0-4392-6e78-a42ee5d2a1c4@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/bdev.c | 2 | ||||
| -rw-r--r-- | block/genhd.c | 1 |
2 files changed, 2 insertions, 1 deletions
diff --git a/block/bdev.c b/block/bdev.c index cf2780cb44a7..485a258b0ab3 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -490,7 +490,6 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno) bdev = I_BDEV(inode); mutex_init(&bdev->bd_fsfreeze_mutex); spin_lock_init(&bdev->bd_size_lock); - bdev->bd_disk = disk; bdev->bd_partno = partno; bdev->bd_inode = inode; bdev->bd_stats = alloc_percpu(struct disk_stats); @@ -498,6 +497,7 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno) iput(inode); return NULL; } + bdev->bd_disk = disk; return bdev; } diff --git a/block/genhd.c b/block/genhd.c index 7b6e5e1cf956..496e8458c357 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1268,6 +1268,7 @@ struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id, out_destroy_part_tbl: xa_destroy(&disk->part_tbl); + disk->part0->bd_disk = NULL; iput(disk->part0->bd_inode); out_free_bdi: bdi_put(disk->bdi); |