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-rw-r--r--arch/riscv/include/asm/uaccess.h7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
index 824b2c9da75b..f944062c9d99 100644
--- a/arch/riscv/include/asm/uaccess.h
+++ b/arch/riscv/include/asm/uaccess.h
@@ -306,7 +306,9 @@ do { \
* data types like structures or arrays.
*
* @ptr must have pointer-to-simple-variable type, and @x must be assignable
- * to the result of dereferencing @ptr.
+ * to the result of dereferencing @ptr. The value of @x is copied to avoid
+ * re-ordering where @x is evaluated inside the block that enables user-space
+ * access (thus bypassing user space protection if @x is a function).
*
* Caller must check the pointer with access_ok() before calling this
* function.
@@ -316,12 +318,13 @@ do { \
#define __put_user(x, ptr) \
({ \
__typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
+ __typeof__(*__gu_ptr) __val = (x); \
long __pu_err = 0; \
\
__chk_user_ptr(__gu_ptr); \
\
__enable_user_access(); \
- __put_user_nocheck(x, __gu_ptr, __pu_err); \
+ __put_user_nocheck(__val, __gu_ptr, __pu_err); \
__disable_user_access(); \
\
__pu_err; \