Messages in this thread | | | Date | Tue, 21 Mar 2023 15:19:18 +0100 | Subject | Re: [PATCH v4 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock | From | David Hildenbrand <> |
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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@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. >> >> 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
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