According to arm procedure call standart r2 register is call-cloberred.
So after the result of x expression was put into r2 any following
function call in p may overwrite r2. To fix this, the result of p
expression must be saved to the temporary variable before the
assigment x expression to __r2.
Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
Reviewed-by: Nicolas Pitre <nico@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
Since v1:
- tmp_p variable renamed to __tmp_p
- added Reviewed-by tag
- added Cc: stable@xxxxxxxxxxxxxxx
arch/arm/include/asm/uaccess.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 12c3a5d..75d9579 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -171,8 +171,9 @@ extern int __put_user_8(void *, unsigned long long);
#define __put_user_check(x,p) \
({ \
unsigned long __limit = current_thread_info()->addr_limit - 1; \
+ const typeof(*(p)) __user *__tmp_p = (p); \
register const typeof(*(p)) __r2 asm("r2") = (x); \
- register const typeof(*(p)) __user *__p asm("r0") = (p);\
+ register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \
register unsigned long __l asm("r1") = __limit; \
register int __e asm("r0"); \
switch (sizeof(*(__p))) { \
--
1.8.5.5
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