Commit 416a8b2c authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: ensure regular inodes for file-backed mounts 



Only regular inodes are allowed for file-backed mounts, not directories
(as seen in the original syzbot case) or special inodes.

Also ensure that .read_folio() is implemented on the underlying fs
for the primary device.

Fixes: fb176750 ("erofs: add file-backed mount support")
Reported-by: default avatar <syzbot+001306cd9c92ce0df23f@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/r/00000000000011bdde0622498ee3@google.com


Tested-by: default avatar <syzbot+001306cd9c92ce0df23f@syzkaller.appspotmail.com>
Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240917130803.32418-1-hsiangkao@linux.alibaba.com
parent 9852d85e

fs/erofs/super.c

+10 −3
Original line number Diff line number Diff line
@@ -191,10 +191,14 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb, 
		if (IS_ERR(file))

			return PTR_ERR(file);



		dif->file = file;

		if (!erofs_is_fileio_mode(sbi))

		if (!erofs_is_fileio_mode(sbi)) {

			dif->dax_dev = fs_dax_get_by_bdev(file_bdev(file),

					&dif->dax_part_off, NULL, NULL);

		} else if (!S_ISREG(file_inode(file)->i_mode)) {

			fput(file);

			return -EINVAL;

		}

		dif->file = file;

	}



	dif->blocks = le32_to_cpu(dis->blocks);
@@ -714,7 +718,10 @@ static int erofs_fc_get_tree(struct fs_context *fc) 
		if (IS_ERR(sbi->fdev))

			return PTR_ERR(sbi->fdev);



		if (S_ISREG(file_inode(sbi->fdev)->i_mode) &&

		    sbi->fdev->f_mapping->a_ops->read_folio)

			return get_tree_nodev(fc, erofs_fc_fill_super);

		fput(sbi->fdev);

	}

#endif

	return ret;