diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 9b96d79eea6c81247380142fb9db0ef1ad0c51cb..708aa1b92036b9d798b1ecccb9f678f633fb1661 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -1135,7 +1135,14 @@ static int nilfs_ioctl_set_alloc_range(struct inode *inode, void __user *argp)
 
 	minseg = range[0] + segbytes - 1;
 	do_div(minseg, segbytes);
+
+	if (range[1] < 4096)
+		goto out;
+
 	maxseg = NILFS_SB2_OFFSET_BYTES(range[1]);
+	if (maxseg < segbytes)
+		goto out;
+
 	do_div(maxseg, segbytes);
 	maxseg--;
 
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index f87563d39b530d1acf2461e09d600aeace1b74aa..2702b48511c5302ab2e204ce6268e1d01bac286f 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -430,6 +430,15 @@ int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
 	if (newsize > devsize)
 		goto out;
 
+	/*
+	 * Prevent underflow in second superblock position calculation.
+	 * The exact minimum size check is done in nilfs_sufile_resize().
+	 */
+	if (newsize < 4096) {
+		ret = -ENOSPC;
+		goto out;
+	}
+
 	/*
 	 * Write lock is required to protect some functions depending
 	 * on the number of segments, the number of reserved segments,
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 484785cdf96e220525a57222190ac3fe0bca7f71..426d5b065306aa027be5a75032a22a484237ba77 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -494,9 +494,15 @@ static int nilfs_load_super_block(struct the_nilfs *nilfs,
 {
 	struct nilfs_super_block **sbp = nilfs->ns_sbp;
 	struct buffer_head **sbh = nilfs->ns_sbh;
-	u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
+	u64 sb2off, devsize = nilfs->ns_bdev->bd_inode->i_size;
 	int valid[2], swp = 0;
 
+	if (devsize < NILFS_SEG_MIN_BLOCKS * NILFS_MIN_BLOCK_SIZE + 4096) {
+		nilfs_msg(sb, KERN_ERR, "device size too small");
+		return -EINVAL;
+	}
+	sb2off = NILFS_SB2_OFFSET_BYTES(devsize);
+
 	sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
 					&sbh[0]);
 	sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);