lkml.org 
[lkml]   [2020]   [Apr]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH RESEND 2/4] uaccess: Selectively open read or write user access
From
Date


Le 02/04/2020 à 09:51, Kees Cook a écrit :
> On Thu, Apr 02, 2020 at 07:34:17AM +0000, Christophe Leroy wrote:
>> [...]
>> diff --git a/kernel/compat.c b/kernel/compat.c
>> index 843dd17e6078..705ca7e418c6 100644
>> --- a/kernel/compat.c
>> +++ b/kernel/compat.c
>> @@ -199,7 +199,7 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
>> bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
>> nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
>>
>> - if (!user_access_begin(umask, bitmap_size / 8))
>> + if (!user_write_access_begin(umask, bitmap_size / 8))
>
> This looks mismatched: should be user_read_access_begin()?

Oops, looks like a copy/paste/modify where I modified the original
instead of the copy.


>
>> return -EFAULT;
>>
>> while (nr_compat_longs > 1) {
>> @@ -211,11 +211,11 @@ long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,
>> }
>> if (nr_compat_longs)
>> unsafe_get_user(*mask, umask++, Efault);
>> - user_access_end();
>> + user_read_access_end();
>> return 0;
>>
>> Efault:
>> - user_access_end();
>> + user_read_access_end();
>> return -EFAULT;
>> }
>
> (These correctly end read access.)
>
>>
>> @@ -228,7 +228,7 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
>> bitmap_size = ALIGN(bitmap_size, BITS_PER_COMPAT_LONG);
>> nr_compat_longs = BITS_TO_COMPAT_LONGS(bitmap_size);
>>
>> - if (!user_access_begin(umask, bitmap_size / 8))
>> + if (!user_read_access_begin(umask, bitmap_size / 8))
>
> And ..._write_... here?
>
>> return -EFAULT;
>>
>> while (nr_compat_longs > 1) {
>> @@ -239,10 +239,10 @@ long compat_put_bitmap(compat_ulong_t __user *umask, unsigned long *mask,
>> }
>> if (nr_compat_longs)
>> unsafe_put_user((compat_ulong_t)*mask, umask++, Efault);
>> - user_access_end();
>> + user_write_access_end();
>> return 0;
>> Efault:
>> - user_access_end();
>> + user_write_access_end();
>> return -EFAULT;
>> }
>
> (These correctly end write access.)
>
>
> All the others look correct. With the above fixed:
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>

Thanks
Christophe

\
 
 \ /
  Last update: 2020-04-02 10:01    [W:0.046 / U:6.556 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site