Messages in this thread | | | Date | Tue, 5 Mar 2019 15:53:06 +0100 | From | Peter Zijlstra <> | Subject | Re: [uaccess] 780464aed0: WARNING:at_arch/x86/include/asm/uaccess.h:#strnlen_user/0x |
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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.GB32534@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.
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