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authorTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>2021-10-02 18:23:02 +0900
committerJens Axboe <axboe@kernel.dk>2021-10-02 07:29:20 -0600
commit06cc978d3ff226072780f74897800b33e78abb57 (patch)
treef8a7767f98974d2bea074848be82708931e5795a /block
parent41e76c6a3c83c85e849f10754b8632ea763d9be4 (diff)
downloadlinux-06cc978d3ff226072780f74897800b33e78abb57.tar.bz2
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.c2
-rw-r--r--block/genhd.c1
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);