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. Since TASK_SIZE is the maximum user space address. The start or len of mlock shouldn't be bigger than this. Function access_ok can be used to check this issue, so return -EINVAL if bigger. Signed-off-by: Ma Wupeng <mawupeng1@xxxxxxxxxx> --- mm/mlock.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/mlock.c b/mm/mlock.c index 7032f6dd0ce1..b9422a62a4cf 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -575,6 +575,9 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla if (!can_do_mlock()) return -EPERM; + if (unlikely(!access_ok((void __user *)start, len))) + return -EINVAL; + len = PAGE_ALIGN(len + (offset_in_page(start))); start &= PAGE_MASK; @@ -635,6 +638,9 @@ SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) start = untagged_addr(start); + if (unlikely(!access_ok((void __user *)start, len))) + return -EINVAL; + len = PAGE_ALIGN(len + (offset_in_page(start))); start &= PAGE_MASK; -- 2.25.1
