From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Date: Wed, 27 Feb 2008 09:02:22 +0100 (CET) > On Tue, 26 Feb 2008, David Miller wrote: > > What the FUTEX checking code is doing now is doing a "user" access > > with set_fs(KERNEL_DS) since it runs from the kernel bootup early init > > sequence. And this is illegal according to the existing checks. > > > > When we do set_fs(KERNEL_DS) then pass a "user" pointer down > > into a system call or something like that, we give it a pointer > > that "cannot fault". So if we get into the fault handling > > path here for a case like that we really do want to scream and > > print out an OOPS message in my opinion. > > So it would be correct to set_fs(USER_DS) then do the check and switch > back to KERNEL_DS ? No, I'm saying it would be better not to take faults purposefully in the kernel address space. We don't have a usable user address space setup at this point in the boot, so using USER_DS would be even worse. I think I'll just add a different version of the sanity check to this sparc64 code later on, one that will take into consideration this KERNEL_DS case because I can see how it could be useful in other circumstances. > > Did this FUTEX change go into -stable too? > > It's queued, AFAIK Crap, I'll need to push my fix there too. - To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
