diff options
Diffstat (limited to 'arch/x86/include/asm/uaccess.h')
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index f13659523108..c9fa7be3df82 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -208,16 +208,24 @@ extern void __put_user_nocheck_2(void); extern void __put_user_nocheck_4(void); extern void __put_user_nocheck_8(void); +/* + * ptr must be evaluated and assigned to the temporary __ptr_pu before + * the assignment of x to __val_pu, to avoid any function calls + * involved in the ptr expression (possibly implicitly generated due + * to KASAN) from clobbering %ax. + */ #define do_put_user_call(fn,x,ptr) \ ({ \ int __ret_pu; \ + void __user *__ptr_pu; \ register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \ __chk_user_ptr(ptr); \ + __ptr_pu = (ptr); \ __val_pu = (x); \ asm volatile("call __" #fn "_%P[size]" \ : "=c" (__ret_pu), \ ASM_CALL_CONSTRAINT \ - : "0" (ptr), \ + : "0" (__ptr_pu), \ "r" (__val_pu), \ [size] "i" (sizeof(*(ptr))) \ :"ebx"); \ |