lkml.org 
[lkml]   [2021]   [Mar]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [PATCH] mm: Return -EFAULT if copy_to_user() fails
Date
From: Wang Qing <wangqing@vivo.com>
> Sent: 01 March 2021 12:33
>
> The copy_to_user() function returns the number of bytes remaining to be
> copied, but we want to return -EFAULT if the copy doesn't complete.
>
> Signed-off-by: Wang Qing <wangqing@vivo.com>
> ---
> mm/mempolicy.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index ab51132..a116e56
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1667,7 +1667,7 @@ COMPAT_SYSCALL_DEFINE5(get_mempolicy, int __user *, policy,
> if (!err && nmask) {
> unsigned long copy_size;
> copy_size = min_t(unsigned long, sizeof(bm), alloc_size);
> - err = copy_from_user(bm, nm, copy_size);
> + err = copy_from_user(bm, nm, copy_size) ? -EFAULT : 0;
> /* ensure entire bitmap is zeroed */
> err |= clear_user(nmask, ALIGN(maxnode-1, 8) / 8);
> err |= compat_put_bitmap(nmask, bm, nr_bits);

Given the 'err |= xxx' that follow I suspect the error code
doesn't matter at all.

David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

\
 
 \ /
  Last update: 2021-03-02 18:39    [W:0.047 / U:1.516 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site