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s390/uaccess: fix possible register corruption in strnlen_user_srst() 

The whole point of the out-of-line strnlen_user_srst() function was to
avoid corruption of register 0 due to register asm assignment.
However 'somebody' :) forgot to remove the update_primary_asce() function
call, which may clobber register 0 contents.
So let's remove that call and also move the size check to the calling
function.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2014-04-09 09:42:58 +02:00 committed by Martin Schwidefsky
parent a960062e58
commit fa255f51c9
1 changed files with 2 additions and 3 deletions
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5
arch/s390/lib/uaccess.c
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@ -338,9 +338,6 @@ static inline unsigned long strnlen_user_srst(const char __user *src,
register unsigned long reg0 asm("0") = 0;
unsigned long tmp1, tmp2;
if (unlikely(!size))
return 0;
update_primary_asce(current);
asm volatile(
" la %2,0(%1)\n"
" la %3,0(%0,%1)\n"
@ -359,6 +356,8 @@ static inline unsigned long strnlen_user_srst(const char __user *src,
unsigned long __strnlen_user(const char __user *src, unsigned long size)
{
if (unlikely(!size))
return 0;
update_primary_asce(current);
return strnlen_user_srst(src, size);
}