Commit 4b15d617 authored by Wenliang Fan's avatar Wenliang Fan Committed by Linus Torvalds

fs/nilfs2: fix integer overflow in nilfs_ioctl_wrap_copy()

The local variable 'pos' in nilfs_ioctl_wrap_copy function can overflow if
a large number was passed to argv->v_index from userspace and the sum of
argv->v_index and argv->v_nmembs exceeds the maximum value of __u64 type
integer (= ~(__u64)0 = 18446744073709551615).

Here, argv->v_index is a 64-bit width argument to specify the start
position of target data items (such as segment number, checkpoint number,
or virtual block address of nilfs), and argv->v_nmembs gives the total
number of the items that userland programs (such as lssu, lscp, or
cleanerd) want to get information about, which also gives the maximum
element count of argv->v_base[] array.

nilfs_ioctl_wrap_copy() calls dofunc() repeatedly and increments the
position variable 'pos' at the end of each iteration if dofunc() itself
didn't update 'pos':

      if (pos == ppos)
              pos += n;

This patch prevents the overflow here by rejecting pairs of a start
position (argv->v_index) and a total count (argv->v_nmembs) which leads to
the overflow.

[konishi.ryusuke@lab.ntt.co.jp: fix signedness issue]
Signed-off-by: default avatarWenliang Fan <fanwlexca@gmail.com>
Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7e775f46
......@@ -57,6 +57,14 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
if (argv->v_size > PAGE_SIZE)
return -EINVAL;
/*
* Reject pairs of a start item position (argv->v_index) and a
* total count (argv->v_nmembs) which leads position 'pos' to
* overflow by the increment at the end of the loop.
*/
if (argv->v_index > ~(__u64)0 - argv->v_nmembs)
return -EINVAL;
buf = (void *)__get_free_pages(GFP_NOFS, 0);
if (unlikely(!buf))
return -ENOMEM;
......
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