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    SubjectRe: [PATCH v2 10/17] lkdtm: use __va_function
    On Thu, Mar 18, 2021 at 10:11 AM Sami Tolvanen <samitolvanen@google.com> wrote:
    >
    > To ensure we take the actual address of a function in kernel text, use
    > __va_function. Otherwise, with CONFIG_CFI_CLANG, the compiler replaces
    > the address with a pointer to the CFI jump table, which is actually in
    > the module when compiled with CONFIG_LKDTM=m.

    Should patch 10 and 12 be reordered against one another? Otherwise it
    looks like 12 defines __va_function while 10 uses it?


    >
    > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
    > Acked-by: Kees Cook <keescook@chromium.org>
    > ---
    > drivers/misc/lkdtm/usercopy.c | 2 +-
    > 1 file changed, 1 insertion(+), 1 deletion(-)
    >
    > diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c
    > index 109e8d4302c1..d173d6175c87 100644
    > --- a/drivers/misc/lkdtm/usercopy.c
    > +++ b/drivers/misc/lkdtm/usercopy.c
    > @@ -314,7 +314,7 @@ void lkdtm_USERCOPY_KERNEL(void)
    >
    > pr_info("attempting bad copy_to_user from kernel text: %px\n",
    > vm_mmap);
    > - if (copy_to_user((void __user *)user_addr, vm_mmap,
    > + if (copy_to_user((void __user *)user_addr, __va_function(vm_mmap),
    > unconst + PAGE_SIZE)) {
    > pr_warn("copy_to_user failed, but lacked Oops\n");
    > goto free_user;
    > --
    > 2.31.0.291.g576ba9dcdaf-goog
    >


    --
    Thanks,
    ~Nick Desaulniers

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