lkml.org 
[lkml]   [2021]   [Dec]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH mm v4 22/39] kasan, fork: reset pointer tags of vmapped stacks
    On Mon, Dec 20, 2021 at 11:01 PM <andrey.konovalov@linux.dev> wrote:
    >
    > From: Andrey Konovalov <andreyknvl@google.com>
    >
    > Once tag-based KASAN modes start tagging vmalloc() allocations,
    > kernel stacks start getting tagged if CONFIG_VMAP_STACK is enabled.
    >
    > Reset the tag of kernel stack pointers after allocation in
    > alloc_thread_stack_node().
    >
    > For SW_TAGS KASAN, when CONFIG_KASAN_STACK is enabled, the
    > instrumentation can't handle the SP register being tagged.
    >
    > For HW_TAGS KASAN, there's no instrumentation-related issues. However,
    > the impact of having a tagged SP register needs to be properly evaluated,
    > so keep it non-tagged for now.
    >
    > Note, that the memory for the stack allocation still gets tagged to
    > catch vmalloc-into-stack out-of-bounds accesses.
    >
    > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
    Reviewed-by: Alexander Potapenko <glider@google.com>
    >
    > ---
    >
    > Changes v2->v3:
    > - Update patch description.
    > ---
    > kernel/fork.c | 1 +
    > 1 file changed, 1 insertion(+)
    >
    > diff --git a/kernel/fork.c b/kernel/fork.c
    > index 403b9dbbfb62..4125373dba4e 100644
    > --- a/kernel/fork.c
    > +++ b/kernel/fork.c
    > @@ -254,6 +254,7 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
    > * so cache the vm_struct.
    > */
    > if (stack) {
    > + stack = kasan_reset_tag(stack);
    > tsk->stack_vm_area = find_vm_area(stack);
    > tsk->stack = stack;
    > }
    > --
    > 2.25.1
    >


    --
    Alexander Potapenko
    Software Engineer

    Google Germany GmbH
    Erika-Mann-Straße, 33
    80636 München

    Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
    Registergericht und -nummer: Hamburg, HRB 86891
    Sitz der Gesellschaft: Hamburg

    \
     
     \ /
      Last update: 2021-12-21 16:12    [W:2.131 / U:0.124 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site