A szybot reproducer that does write I/O while truncating the size of a
block device can end up in clean_bdev_aliases, which tries to clean the
bdev aliases that it uses. This is because iomap_to_bh automatically
sets the BH_New flag when outside of i_size. For block devices updates
to i_size are racy and we can hit this case in a tiny race window,
leading to the eventual clean_bdev_aliases call. Fix this by erroring
out of > i_size I/O on block devices.
Reported-by: syzbot+1fa947e7f09e136925b8@syzkaller.appspotmail.com
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: syzbot+1fa947e7f09e136925b8@syzkaller.appspotmail.com
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
fallthrough;
case IOMAP_MAPPED:
if ((iomap->flags & IOMAP_F_NEW) ||
- offset >= i_size_read(inode))
+ offset >= i_size_read(inode)) {
+ /*
+ * This can happen if truncating the block device races
+ * with the check in the caller as i_size updates on
+ * block devices aren't synchronized by i_rwsem for
+ * block devices.
+ */
+ if (S_ISBLK(inode->i_mode))
+ return -EIO;
set_buffer_new(bh);
+ }
bh->b_blocknr = (iomap->addr + offset - iomap->offset) >>
inode->i_blkbits;
set_buffer_mapped(bh);