On Mon, Nov 30, 2020 at 04:07:03PM +0800, Pekka Enberg wrote: Hi Pekka, > On Mon, Nov 30, 2020 at 7:33 AM Eric Lin <[email protected]> wrote: > > > > In the page fault handler, an access to user-space memory > > without get/put_user() or copy_from/to_user() routines is > > not resolved properly. Like arm and other architectures, > > we need to let it die earlier in page fault handler. > > Fix looks good to me. Can you elaborate on how you found the issue and > how the bug manifests itself?
OK, I'll elaborate more on the commit message. > > > > > Signed-off-by: Eric Lin <[email protected]> > > Cc: Alan Kao <[email protected]> > > --- > > arch/riscv/mm/fault.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c > > index 3c8b9e433c67..a452cfa266a2 100644 > > --- a/arch/riscv/mm/fault.c > > +++ b/arch/riscv/mm/fault.c > > @@ -232,6 +232,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs) > > if (user_mode(regs)) > > flags |= FAULT_FLAG_USER; > > > > + if (!user_mode(regs) && addr < TASK_SIZE && unlikely(!(regs->status > > & SR_SUM))) > > + die(regs, "Accessing user space memory without uaccess > > routines\n"); > > Let's introduce a die_kernel_fault() helper (similar to arm64, for > example) to ensure same semantics for the different kernel faults. You > can extract the helper from no_context(). OK, I'll add a die_kernel_fault() helper function in v2. Thanks for your review. > > > + > > perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); > > > > if (cause == EXC_STORE_PAGE_FAULT) > > -- > > 2.17.0 > > > > > > _______________________________________________ > > linux-riscv mailing list > > [email protected] > > http://lists.infradead.org/mailman/listinfo/linux-riscv
