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SubjectRe: [PATCH] fs/fcntl: Fix F_GET/SETLK etc. for compat processes
On Fri, Jul 07, 2017 at 10:48:51PM +1000, Michael Ellerman wrote:
> Commit 8c6657cb50cb ("Switch flock copyin/copyout primitives to
> copy_{from,to}_user()") added copy_flock_fields(from, to), but then in all cases
> called it with arguments of (to, from). eg:
>
> static int get_compat_flock(struct flock *kfl, 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);
> return 0;
> }
>
> We are reading the compat_flock ufl from userspace, into flock kfl. First we
> copy all of ufl into fl on the stack, and then we want to assign each field of
> fl to kfl. So we are copying from fl and to kfl. But as written the
> copy_flock_fields() macro takes the arguments in the other order.
>
> copy_to/from_user() take "to" as the first argument, so change the order of
> arguments in the copy_flock_fields() macro, rather than changing the callers.

D'oh...

Acked-by: Al Viro <viro@zeniv.linux.org.uk>

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