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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 Content-Language: en-US To: , References: <20230320024739.224850-1-mawupeng1@huawei.com> <20230320024739.224850-2-mawupeng1@huawei.com> <27b9cb5b-0118-f989-80c2-6a143a4232af@redhat.com> 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: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500014.china.huawei.com (7.185.36.153) X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 2C47B180020 X-Stat-Signature: rkr8tfjnx6iarqkkw9is9bihwtpfqt5c X-HE-Tag: 1679310338-874265 X-HE-Meta: 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 wNjsBUaW VwCiPM5P6gevx+6VrvEtL/0XNmrV1Zih0JFeLttHw9BVcCwqn6Xvv/UeNwt9AYSGuUtXUA19kxAMGGh1v9sdlrawpdfOQxRFqSIG1AJW3vVA0PVVAFB8Jv3AaYZZ7A4wHnMbln7u3GrRBgiQP03Z5xDfAzKEyCQsufdQodrxaoUIchcxxiUA9vL/xDAcrCgLBjoyv 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? Thanks for reviewing. I will test this and resend & reply this. > >> >> 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) Sorry for wasting your time. I send the wrong version of this patchset, this is the older version. > >> +        return -EINVAL; >> + >>       if (mmap_write_lock_killable(current->mm)) >>           return -EINTR; >>       ret = apply_vma_lock_flags(start, len, 0); >