x86: copy_from_user() should not return -EFAULT
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>
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 0c9825e..088d09f 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -205,14 +205,13 @@
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,
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 46324c6..535e4214 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -30,16 +30,15 @@
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