On 21.03.23 08:44, mawupeng wrote:
On 2023/3/20 18:54, David Hildenbrand wrote:
On 20.03.23 03:47, Wupeng Ma wrote:
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.
Thinking again, wouldn't we reject mlock(0, ULONG_MAX) now as well?
mlock will return 0 if len is zero which is the same w/o this patchset.
Here is the calltrace if len is zero.
mlock(len == 0)
do_mlock(len == 0)
if (!len)
return 0
I was asking about addr=0, len=ULONG_MAX.
IIUC, that used to work but could now fail? I haven't played with it,
though.
--
Thanks,
David / dhildenb
