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x86: copy_from_user() should not return -EFAULT

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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>
This commit is contained in:
Heiko Carstens 2010-01-05 14:19:11 +01:00 committed by H. Peter Anvin
parent f4b825bde9
commit 409d02ef6d
2 changed files with 4 additions and 6 deletions
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5
arch/x86/include/asm/uaccess_32.h
View 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,

5
arch/x86/include/asm/uaccess_64.h
View 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