On Tue, 5 Mar 2019 11:36:35 +0900 Masami Hiramatsu <mhira...@kernel.org> wrote:
> On Mon, 4 Mar 2019 10:59:22 -0800 > Linus Torvalds <torva...@linux-foundation.org> wrote: > > I think the better way to do this is allowing strncpy_from_user() > if some conditions are match, like > > - strncpy_from_user() will be able to copy user memory with set_fs(USER_DS) > - strncpy_from_user() can copy kernel memory with set_fs(KERNEL_DS) > - strncpy_from_user() can access unsafe memory in IRQ context if > pagefault is disabled. > > This is almost done, except for CONFIG_DEBUG_ATOMIC_SLEEP=y on x86. > > So, what about adding a condition to WARN_ON_IN_IRQ() like below > instead of introducing user_access_ok() ? > > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h > index 780f2b42c8ef..ec0f0b74c9ab 100644 > --- a/arch/x86/include/asm/uaccess.h > +++ b/arch/x86/include/asm/uaccess.h > @@ -70,7 +70,7 @@ static inline bool __chk_range_not_ok(unsigned long addr, > unsigned long size, un > }) > > #ifdef CONFIG_DEBUG_ATOMIC_SLEEP > -# define WARN_ON_IN_IRQ() WARN_ON_ONCE(!in_task()) > +# define WARN_ON_IN_IRQ() WARN_ON_ONCE(pagefault_disabled() && > !in_task()) Oops, I meant !pagefault_disabled() && !in_task(). > #else > # define WARN_ON_IN_IRQ() > #endif > > Of course we have to move pagefault_disabled() macro in somewhere better > place. And I think we don't need it. anyway the macro is referenced via linux/uaccess.h. Thank you, -- Masami Hiramatsu <mhira...@kernel.org>
