From: Ma Wupeng <mawupeng1@xxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxx/T/
[2]: https://lore.kernel.org/linux-mm/20230116115813.2956935-5-mawupeng1@xxxxxxxxxx/T/
[3]: https://lore.kernel.org/linux-mm/de4149c7-0e6e-2035-3fb8-2f9da9633704@xxxxxxxxxx/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
