On Tue, Mar 05, 2019 at 10:58:01PM +0900, Masami Hiramatsu wrote: > Could you tell me why WARN_ON_ONCE(!in_task()) is needed in access_ok()?
That came from here: lkml.kernel.org/r/20190225145240.gb32...@hirez.programming.kicks-ass.net Because in-irq usage is dodgy, since we don't actually know what mm or ds it loaded. > > I dislike that whole KERNEL_DS thing, but obviously that's not something > > that's going away. > > > > Would something like: > > > > WARN_ON_ONCE(!(in_task || segment_eq(get_fs(), USER_DS))) > > > > Work? Then we allow KERNEL_DS in task context, but for interrupt and > > others require USER_DS. > > But what would this mean? I can't understand why we limit using > access_ok() so strictly and narrow the cases. Because it's been a source of bugs. Any sanity checking we can put in seems like a good thing at this point.
