lkml.org 
[lkml]   [2023]   [Mar]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH v4 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock
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

\
 
 \ /
  Last update: 2023-03-27 01:08    [W:0.099 / U:0.496 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site