[PATCH v2 0/4] Add overflow checks for several syscalls

[Wupeng Ma <mawupeng1@huawei.com>]

From: Ma Wupeng <mawupeng1@huawei.com>

While testing mlock, we have a problem if the len of mlock is ULONG_MAX.
The return value of mlock is zero. But nothing will be locked since the
len in do_mlock overflows to zero due to the following code in mlock:

  len = PAGE_ALIGN(len + (offset_in_page(start)));

The same problem happens in munlock.

Add new check and return -EINVAL to fix this overflowing scenarios since
they are absolutely wrong.

Similar logic is used to fix problems with multiple syscalls.

Changelog since v1[1]:
- only check overflow rather than access_ok to keep backward-compatibility

[1]: https://lore.kernel.org/lkml/20221228141701.c64add46c4b09aa17f605baf@linux-foundation.org/T/

Ma Wupeng (4):
  mm/mlock: return EINVAL if len overflows for mlock/munlock
  mm/mempolicy: return EINVAL for if len overflows for
    set_mempolicy_home_node
  mm/mempolicy: return EINVAL if len overflows for mbind
  mm/msync: return ENOMEM if len overflows for msync

 mm/mempolicy.c | 6 ++++--
 mm/mlock.c     | 8 ++++++++
 mm/msync.c     | 3 ++-
 3 files changed, 14 insertions(+), 3 deletions(-)

-- 
2.25.1