Date:   Mon, 20 Mar 2023 10:47:35 +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>, <david@...hat.com>
Subject: [PATCH v4 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.

Here is the testcases:

  #include <stdio.h>
  #define _GNU_SOURCE
  #include <sys/mman.h>
  #include <fcntl.h>
  #include <errno.h>
  #include <unistd.h>
  #include <string.h>
  #include <limits.h>
  #include <numaif.h>
  
  extern int errno;
  int main(void)
  {
      int fd;
      int ret;
      void *addr;
      int size = getpagesize();
  
      fd = open("/tmp/testfile", O_RDWR | O_CREAT);
      if (fd < 0) {
          printf("open file error! errno: %d\n", errno);
          return -1;
      }
      printf("open success\n");
      addr = mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
      if (addr == MAP_FAILED) {
          printf("open file error! errno: %d\n", errno);
          close(fd);
          return -1;
      }
      printf("mmap success\n");
      memset(addr, 0, size);
  
      printf("==== mlock ====\n");
      ret = mlock(addr, ULONG_MAX);
      if (ret == -1 && errno == EINVAL)
          printf("mlock test passed\n");
      else
          printf("mlock test failed, ret: %d, errno: %d\n", ret, errno);
  
      printf("==== set_mempolicy_home_node ====\n");
      ret = syscall(450, addr, ULONG_MAX, 0, 0);
      if (ret == -1 && errno == EINVAL)
          printf("set_mempolicy_home_node test passed\n");
      else
          printf("set_mempolicy_home_node test failed, ret: %d, errno: %d\n", ret, errno);
  
      printf("==== mbind ====\n");
      unsigned long nodemask = 1Ul << 0;
      long max_node = 8 * sizeof(nodemask);
      ret = mbind(addr, ULONG_MAX, MPOL_BIND, &nodemask, max_node, MPOL_MF_MOVE_ALL);
      if (ret == -1 && errno == EINVAL)
          printf("mbind test passed\n");
      else
          printf("mbind test failed, ret: %d, errno: %d\n", ret, errno);
  
      printf("==== msync ====\n");
      ret = msync(addr, ULONG_MAX, MS_ASYNC);
      if (ret == -1 && errno == ENOMEM)
          printf("mbind test passed\n");
      else
          printf("mbind test failed, ret: %d, errno: %d\n", ret, errno);
  
      munmap(mmap, size);
  
      return 0;
  }

Changelog since v3[3]:
- rebase to the latest master
- add simple testcases

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/
[3]: https://lore.kernel.org/linux-mm/de4149c7-0e6e-2035-3fb8-2f9da9633704@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 | 6 ++++--
 mm/mlock.c     | 8 ++++++++
 mm/msync.c     | 3 ++-
 3 files changed, 14 insertions(+), 3 deletions(-)

-- 
2.25.1

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