Commit 409d02ef authored by Heiko Carstens's avatar Heiko Carstens Committed by H. Peter Anvin

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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: default avatarArjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20100105131911.GC5480@osiris.boeblingen.de.ibm.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent f4b825bd
...@@ -205,14 +205,13 @@ static inline unsigned long __must_check copy_from_user(void *to, ...@@ -205,14 +205,13 @@ static inline unsigned long __must_check copy_from_user(void *to,
unsigned long n) unsigned long n)
{ {
int sz = __compiletime_object_size(to); int sz = __compiletime_object_size(to);
int ret = -EFAULT;
if (likely(sz == -1 || sz >= n)) if (likely(sz == -1 || sz >= n))
ret = _copy_from_user(to, from, n); n = _copy_from_user(to, from, n);
else else
copy_from_user_overflow(); copy_from_user_overflow();
return ret; return n;
} }
long __must_check strncpy_from_user(char *dst, const char __user *src, long __must_check strncpy_from_user(char *dst, const char __user *src,
......
...@@ -30,16 +30,15 @@ static inline unsigned long __must_check copy_from_user(void *to, ...@@ -30,16 +30,15 @@ static inline unsigned long __must_check copy_from_user(void *to,
unsigned long n) unsigned long n)
{ {
int sz = __compiletime_object_size(to); int sz = __compiletime_object_size(to);
int ret = -EFAULT;
might_fault(); might_fault();
if (likely(sz == -1 || sz >= n)) if (likely(sz == -1 || sz >= n))
ret = _copy_from_user(to, from, n); n = _copy_from_user(to, from, n);
#ifdef CONFIG_DEBUG_VM #ifdef CONFIG_DEBUG_VM
else else
WARN(1, "Buffer overflow detected!\n"); WARN(1, "Buffer overflow detected!\n");
#endif #endif
return ret; return n;
} }
static __always_inline __must_check static __always_inline __must_check
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment