From 06cc978d3ff226072780f74897800b33e78abb57 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Sat, 2 Oct 2021 18:23:02 +0900 Subject: 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 Signed-off-by: Tetsuo Handa Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/e6dd13c5-8db0-4392-6e78-a42ee5d2a1c4@i-love.sakura.ne.jp Signed-off-by: Jens Axboe --- block/bdev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block/bdev.c') 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; } -- cgit v1.2.3