From: David Hildenbrand <david@redhat.com>
To: Wupeng Ma <mawupeng1@huawei.com>, akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kuleshovmail@gmail.com, aneesh.kumar@linux.ibm.com
Subject: Re: [PATCH v4 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock
Date: Mon, 20 Mar 2023 11:54:11 +0100 [thread overview]
Message-ID: <27b9cb5b-0118-f989-80c2-6a143a4232af@redhat.com> (raw)
In-Reply-To: <20230320024739.224850-2-mawupeng1@huawei.com>
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?
>
> Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
> ---
> 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);
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2023-03-20 10:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-20 2:47 [PATCH v4 0/4] Add overflow checks for several syscalls Wupeng Ma
2023-03-20 2:47 ` [PATCH v4 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock Wupeng Ma
2023-03-20 10:54 ` David Hildenbrand [this message]
2023-03-20 11:05 ` mawupeng
2023-03-21 7:44 ` mawupeng
2023-03-21 14:19 ` David Hildenbrand
2023-03-22 2:14 ` mawupeng
2023-03-22 8:54 ` David Hildenbrand
2023-03-22 9:01 ` David Hildenbrand
2023-03-22 9:20 ` mawupeng
2023-03-22 11:27 ` David Hildenbrand
2023-03-20 2:47 ` [PATCH v4 2/4] mm/mempolicy: return EINVAL for if len overflows for set_mempolicy_home_node Wupeng Ma
2023-03-20 2:47 ` [PATCH v4 3/4] mm/mempolicy: return EINVAL if len overflows for mbind Wupeng Ma
2023-03-20 2:47 ` [PATCH v4 4/4] mm/msync: return ENOMEM if len overflows for msync Wupeng Ma
2023-03-20 11:06 ` [PATCH v4 0/4] Add overflow checks for several syscalls mawupeng
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