nilfs2: avoid overflowing segment numbers in nilfs_ioctl_clean_segments()

nsegs is read from userspace.  Limit its value and avoid overflowing nsegs
* sizeof(__u64) in the subsequent call to memdup_user().

This patch complements 481fe17e973fb9 ("nilfs2: potential integer overflow
in nilfs_ioctl_clean_segments()").

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Cc: Haogang Chen <haogangchen@gmail.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <haogangchen@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
nilfs2: fix NULL pointer dereference in nilfs_load_super_block()

According to the report from Slicky Devil, nilfs caused kernel oops at
nilfs_load_super_block function during mount after he shrank the
partition without resizing the filesystem:

 BUG: unable to handle kernel NULL pointer dereference at 00000048
 IP: [<d0d7a08e>] nilfs_load_super_block+0x17e/0x280 [nilfs2]
 *pde = 00000000
 Oops: 0000 [#1] PREEMPT SMP
 ...
 Call Trace:
  [<d0d7a87b>] init_nilfs+0x4b/0x2e0 [nilfs2]
  [<d0d6f707>] nilfs_mount+0x447/0x5b0 [nilfs2]
  [<c0226636>] mount_fs+0x36/0x180
  [<c023d961>] vfs_kern_mount+0x51/0xa0
  [<c023ddae>] do_kern_mount+0x3e/0xe0
  [<c023f189>] do_mount+0x169/0x700
  [<c023fa9b>] sys_mount+0x6b/0xa0
  [<c04abd1f>] sysenter_do_call+0x12/0x28
 Code: 53 18 8b 43 20 89 4b 18 8b 4b 24 89 53 1c 89 43 24 89 4b 20 8b 43
 20 c7 43 2c 00 00 00 00 23 75 e8 8b 50 68 89 53 28 8b 54 b3 20 <8b> 72
 48 8b 7a 4c 8b 55 08 89 b3 84 00 00 00 89 bb 88 00 00 00
 EIP: [<d0d7a08e>] nilfs_load_super_block+0x17e/0x280 [nilfs2] SS:ESP 0068:ca9bbdcc
 CR2: 0000000000000048

This turned out due to a defect in an error path which runs if the
calculated location of the secondary super block was invalid.

This patch fixes it and eliminates the reported oops.

Reported-by: Slicky Devil <slicky.dvl@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Slicky Devil <slicky.dvl@gmail.com>
Cc: <stable@vger.kernel.org>	[2.6.30+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
nilfs2: potential integer overflow in nilfs_ioctl_clean_segments()

There is a potential integer overflow in nilfs_ioctl_clean_segments().
When a large argv[n].v_nmembs is passed from the userspace, the subsequent
call to vmalloc() will allocate a buffer smaller than expected, which
leads to out-of-bound access in nilfs_ioctl_move_blocks() and
lfs_clean_segments().

The following check does not prevent the overflow because nsegs is also
controlled by the userspace and could be very large.

		if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment)
			goto out_free;

This patch clamps argv[n].v_nmembs to UINT_MAX / argv[n].v_size, and
returns -EINVAL when overflow.

Signed-off-by: Haogang Chen <haogangchen@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>