On Fri, Apr 02, 2021 at 10:04:23AM +0200, Christian Brauner wrote: > On Fri, Apr 02, 2021 at 12:33:20AM -0700, Omar Sandoval wrote: > > On Thu, Apr 01, 2021 at 09:05:22AM -0700, Linus Torvalds wrote: > > > On Wed, Mar 31, 2021 at 11:51 PM Omar Sandoval <osandov@xxxxxxxxxxx> wrote: > > > > > > > > + * > > > > + * The recommended usage is something like the following: > > > > + * > > > > + * if (usize > PAGE_SIZE) > > > > + * return -E2BIG; > > > > > > Maybe this should be more than a recommendation, and just be inside > > > copy_struct_from_iter(), because otherwise the "check_zeroed_user()" > > > call might be quite the timesink for somebody who does something > > > stupid. > > > > I did actually almost send this out with the check in > > copy_struct_from_iter(), but decided not to for consistency with > > copy_struct_from_user(). > > > > openat2() seems to be the only user of copy_struct_from_user() that > > doesn't limit to PAGE_SIZE, which is odd given that Aleksa wrote both > > Al said there's nothing wrong with copying large chunks of memory so we > shouldn't limit the helper but instead limit the callers which have > expectations about their size limit: > https://lore.kernel.org/lkml/20190905182801.GR1131@xxxxxxxxxxxxxxxxxx/ Thanks for the context. So I guess it makes sense to keep the check "recommended" for both functions.
