IBM Research - SSD-n végrehajtott rowhammer-szerű támadással root jog szerezhető

5.1 Other filesystems

Although many parts of the attack described in Section 4 can be generalized, it remains dependent on filesystems using indirect blocks, such as ext3, ext2, and some versions of the Unix File System (UFS1). The ext4 filesystem uses extents (as NTFS does as well), essentially describing data blocks as a set of (starting file block, starting disk block, number of blocks) tuples. Although it is possible to have an “extent block” in ext4 (beyond 3 extents, ext4 starts storing extents in a new block outside of the inode, thereby starting a tree structure), we believe the attack would have a much lower probability of success because of the greater structure of extents (i.e., it is much less likely that a random corruption will not be caught by the ext4 parser: this is compounded by the fact that ext4 typically uses a block number space of 48 bits, instead of ext3’s 32 bits). Therefore, whether the attack would still be feasible for other filesystems remains to be seen.