Re: [git pull] vfs.git part 1

[Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>]

On Fri, Jul 7, 2017 at 5:46 AM, Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
> Al Viro <viro@xxxxxxxxxxxxxxxxxx> writes:
>
>>
>>   Switch flock copyin/copyout primitives to copy_{from,to}_user() (2017-06-26 23:52:44 -0400)
>
> This commit seems to have broken networking on a bunch of my PPC
> machines (64-bit kernel, 32-bit userspace).

Bah. I think that commit is entirely broken, due to having the
arguments to the "copy_flock_fields()" in the wrong order.

The copy_flock_fields() macro has the arguments in order <from, to>,
but all the users seem to do it the other way around.

I think it would have been more obvious if the put_compat_flock*()
source argument had been "const".

> Patch coming.

I'm not seeing a patch, so I did my own. But it's _entirely_ untested.
Does the attached fix things for you?

                     Linus

 fs/fcntl.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/fcntl.c b/fs/fcntl.c
index b6bd89628025..eeb19e22fd08 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -527,43 +527,43 @@ SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 	(to).l_len = (from).l_len;		\
 	(to).l_pid = (from).l_pid;
 
-static int get_compat_flock(struct flock *kfl, struct compat_flock __user *ufl)
+static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl)
 {
 	struct compat_flock fl;
 
 	if (copy_from_user(&fl, ufl, sizeof(struct compat_flock)))
 		return -EFAULT;
-	copy_flock_fields(*kfl, fl);
+	copy_flock_fields(fl, *kfl);
 	return 0;
 }
 
-static int get_compat_flock64(struct flock *kfl, struct compat_flock64 __user *ufl)
+static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl)
 {
 	struct compat_flock64 fl;
 
 	if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64)))
 		return -EFAULT;
-	copy_flock_fields(*kfl, fl);
+	copy_flock_fields(fl, *kfl);
 	return 0;
 }
 
-static int put_compat_flock(struct flock *kfl, struct compat_flock __user *ufl)
+static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl)
 {
 	struct compat_flock fl;
 
 	memset(&fl, 0, sizeof(struct compat_flock));
-	copy_flock_fields(fl, *kfl);
+	copy_flock_fields(*kfl, fl);
 	if (copy_to_user(ufl, &fl, sizeof(struct compat_flock)))
 		return -EFAULT;
 	return 0;
 }
 
-static int put_compat_flock64(struct flock *kfl, struct compat_flock64 __user *ufl)
+static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl)
 {
 	struct compat_flock64 fl;
 
 	memset(&fl, 0, sizeof(struct compat_flock64));
-	copy_flock_fields(fl, *kfl);
+	copy_flock_fields(*kfl, fl);
 	if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64)))
 		return -EFAULT;
 	return 0;