Commit 11e9b4ed authored by Al Viro's avatar Al Viro Committed by Sasha Levin

asm-generic: make copy_from_user() zero the destination properly

[ Upstream commit 2545e5da ]

... in all cases, including the failing access_ok()

Note that some architectures using asm-generic/uaccess.h have
__copy_from_user() not zeroing the tail on failure halfway
through.  This variant works either way.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent 62fc2f90
......@@ -255,11 +255,13 @@ extern int __get_user_bad(void) __attribute__((noreturn));
static inline long copy_from_user(void *to,
const void __user * from, unsigned long n)
{
unsigned long res = n;
might_fault();
if (access_ok(VERIFY_READ, from, n))
return __copy_from_user(to, from, n);
else
return n;
if (likely(access_ok(VERIFY_READ, from, n)))
res = __copy_from_user(to, from, n);
if (unlikely(res))
memset(to + (n - res), 0, res);
return res;
}
static inline long copy_to_user(void __user *to,
......
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