x86: copy_from_user() should not return -EFAULT
authorHeiko Carstens <heiko.carstens@de.ibm.com>
Tue, 5 Jan 2010 13:19:11 +0000 (14:19 +0100)
committerH. Peter Anvin <hpa@zytor.com>
Tue, 5 Jan 2010 21:45:06 +0000 (13:45 -0800)
Callers of copy_from_user() expect it to return the number of bytes
it could not copy. In no case it is supposed to return -EFAULT.

In case of a detected buffer overflow just return the requested
length. In addition one could think of a memset that would clear
the size of the target object.

[ hpa: code is not in .32 so not needed for -stable ]

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20100105131911.GC5480@osiris.boeblingen.de.ibm.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
arch/x86/include/asm/uaccess_32.h
arch/x86/include/asm/uaccess_64.h

index 0c9825e97f361fd40032ac8d3417318288a864b2..088d09fb1615af8081872b04e9b2b3ec15e1fbad 100644 (file)
@@ -205,14 +205,13 @@ static inline unsigned long __must_check copy_from_user(void *to,
                                          unsigned long n)
 {
        int sz = __compiletime_object_size(to);
-       int ret = -EFAULT;
 
        if (likely(sz == -1 || sz >= n))
-               ret = _copy_from_user(to, from, n);
+               n = _copy_from_user(to, from, n);
        else
                copy_from_user_overflow();
 
-       return ret;
+       return n;
 }
 
 long __must_check strncpy_from_user(char *dst, const char __user *src,
index 46324c6a4f6e3da0aba2f3a6576ade498c3ea57b..535e421498f6148ed36adaf698f54a13c58393de 100644 (file)
@@ -30,16 +30,15 @@ static inline unsigned long __must_check copy_from_user(void *to,
                                          unsigned long n)
 {
        int sz = __compiletime_object_size(to);
-       int ret = -EFAULT;
 
        might_fault();
        if (likely(sz == -1 || sz >= n))
-               ret = _copy_from_user(to, from, n);
+               n = _copy_from_user(to, from, n);
 #ifdef CONFIG_DEBUG_VM
        else
                WARN(1, "Buffer overflow detected!\n");
 #endif
-       return ret;
+       return n;
 }
 
 static __always_inline __must_check