Mailing List Archive

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.

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 V4:
- send the right version of this patchset

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

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