nilfs2: clamp ns_r_segments_percentage to [1, 99]

ns_r_segments_percentage is read from the disk. Bogus or malicious value could cause integer overflow and malfunction due to meaningless disk usage calculation. This patch reports error when mounting such bogus volumes. Signed-off-by: Haogang Chen <[email protected]> Signed-off-by: Ryusuke Konishi <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
maraz · Mar 17, 2012 · 3d777a6 · 3d777a6
1 parent cf2b94d
commit 3d777a6
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
@@ -409,6 +409,12 @@ static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
 	nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
 	nilfs->ns_r_segments_percentage =
 		le32_to_cpu(sbp->s_r_segments_percentage);
+	if (nilfs->ns_r_segments_percentage < 1 ||
+	    nilfs->ns_r_segments_percentage > 99) {
+		printk(KERN_ERR "NILFS: invalid reserved segments percentage.\n");
+		return -EINVAL;
+	}
+
 	nilfs_set_nsegments(nilfs, le64_to_cpu(sbp->s_nsegments));
 	nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
 	return 0;