futex: Sanitize cmpxchg_futex_value_locked API

[linux-flexiantxendom0.git] / arch / x86 / include / asm / futex.h

diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
index 1f11ce4..884c0b5 100644 (file)
--- a/arch/x86/include/asm/futex.h
+++ b/arch/x86/include/asm/futex.h
@@ -109,9 +109,10 @@ static inline int futex_atomic_op_inuser(int encoded_op, int __user *uaddr)
        return ret;
 }
 
-static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval,
-                                               int newval)
+static inline int futex_atomic_cmpxchg_inatomic(int *uval, int __user *uaddr,
+                                               int oldval, int newval)
 {
+       int ret = 0;
 
 #if defined(CONFIG_X86_32) && !defined(CONFIG_X86_BSWAP)
        /* Real i386 machines have no cmpxchg instruction */
@@ -122,18 +123,19 @@ static inline int futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval,
        if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
                return -EFAULT;
 
-       asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %3, %1\n"
+       asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"
                     "2:\t.section .fixup, \"ax\"\n"
-                    "3:\tmov     %2, %0\n"
+                    "3:\tmov     %3, %0\n"
                     "\tjmp     2b\n"
                     "\t.previous\n"
                     _ASM_EXTABLE(1b, 3b)
-                    : "=a" (oldval), "+m" (*uaddr)
-                    : "i" (-EFAULT), "r" (newval), "0" (oldval)
+                    : "+r" (ret), "=a" (oldval), "+m" (*uaddr)
+                    : "i" (-EFAULT), "r" (newval), "1" (oldval)
                     : "memory"
        );
 
-       return oldval;
+       *uval = oldval;
+       return ret;
 }
 
 #endif