linux-kernel - [PATCH v3 0/4] Add overflow checks for several syscalls

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Date:   Sat, 28 Jan 2023 14:32:25 +0800
From:   Wupeng Ma <mawupeng1@...wei.com>
To:     <akpm@...ux-foundation.org>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <mawupeng1@...wei.com>, <kuleshovmail@...il.com>,
        <aneesh.kumar@...ux.ibm.com>
Subject: [PATCH v3 0/4] Add overflow checks for several syscalls

From: Ma Wupeng <mawupeng1@...wei.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 v2[2]:
- modified the way of checking overflows based on Andrew's comments

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/
[2]: https://lore.kernel.org/linux-mm/20230116115813.2956935-5-mawupeng1@huawei.com/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 | 18 ++++++++++++------
 mm/mlock.c     | 14 ++++++++++++--
 mm/msync.c     |  9 ++++++---
 3 files changed, 30 insertions(+), 11 deletions(-)

-- 
2.25.1