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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 CC: , , , , Subject: Re: [PATCH v4 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock To: , References: <20230320024739.224850-1-mawupeng1@huawei.com> <20230320024739.224850-2-mawupeng1@huawei.com> <27b9cb5b-0118-f989-80c2-6a143a4232af@redhat.com> Content-Language: en-US From: mawupeng In-Reply-To: <27b9cb5b-0118-f989-80c2-6a143a4232af@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.120] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500014.china.huawei.com (7.185.36.153) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 7A242100003 X-Stat-Signature: todhgskdgy1eubia8ezepmsapq4nsqdy X-Rspam-User: X-HE-Tag: 1679384691-139743 X-HE-Meta: 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 HlxyWWrG X1eL+OOZf9XOR1DpFtE+ZeuzfrVyi5xVZw9GrU6Jfv52PrnzWnab8VsJ6rmrWGiVUMnQpr7fOGIbb/ma9fwBmIDHfJyPUYfFi9+pOjA3+eEqyDG9QUhPvmYykG/pQ4gfL1gQlc36D0RU0/qBwT/C25OxqvqM+4rtVwR1Jg3Dcb7WUkB9ArvYUUXG+6LcTv/Bj2LiIzuabgBFkMoiPpXekaeldiAboh/ex44gYloMQcelCuRM= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023/3/20 18:54, David Hildenbrand wrote: > On 20.03.23 03:47, Wupeng Ma wrote: >> From: Ma Wupeng >> >> 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 Sorry for wasting your time in the wrong v4. Here is the latest v5: https://patchwork.kernel.org/project/linux-mm/list/?series=732216 > >> >> Signed-off-by: Ma Wupeng >> --- >>   mm/mlock.c | 8 ++++++++ >>   1 file changed, 8 insertions(+) >> >> diff --git a/mm/mlock.c b/mm/mlock.c >> index 617469fce96d..eb68476da497 100644 >> --- a/mm/mlock.c >> +++ b/mm/mlock.c >> @@ -568,6 +568,7 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla >>       unsigned long locked; >>       unsigned long lock_limit; >>       int error = -ENOMEM; >> +    size_t old_len = len; >>         start = untagged_addr(start); >>   @@ -577,6 +578,9 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla >>       len = PAGE_ALIGN(len + (offset_in_page(start))); >>       start &= PAGE_MASK; >>   +    if (old_len != 0 && len == 0) > > if (old_len && !len) > >> +        return -EINVAL; >> + >>       lock_limit = rlimit(RLIMIT_MEMLOCK); >>       lock_limit >>= PAGE_SHIFT; >>       locked = len >> PAGE_SHIFT; >> @@ -631,12 +635,16 @@ SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags) >>   SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len) >>   { >>       int ret; >> +    size_t old_len = len; >>         start = untagged_addr(start); >>         len = PAGE_ALIGN(len + (offset_in_page(start))); >>       start &= PAGE_MASK; >>   +    if (old_len != 0 && len == 0) > > if (old_len && !len) > >> +        return -EINVAL; >> + >>       if (mmap_write_lock_killable(current->mm)) >>           return -EINTR; >>       ret = apply_vma_lock_flags(start, len, 0); >