On Wed, 4 Nov 2015, Zhou Chengming wrote:
> When enable KASLR, func->old_addr will be set to zero
> and livepatch will find the right old address.
> But for reloc, livepatch just verify it using reloc->val
> (old addr from user), so verify failed and report
> "kernel mismatch" error.
>
> Reported-by: Cyril B. <c...@alwaysdata.com>
> Signed-off-by: Zhou Chengming <zhouchengmi...@huawei.com>
> ---
> kernel/livepatch/core.c | 7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 53196e2..c8885c6 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -311,7 +311,12 @@ static int klp_write_object_relocations(struct module
> *pmod,
> return -EINVAL;
>
> for (reloc = obj->relocs; reloc->name; reloc++) {
> - if (!klp_is_module(obj)) {
> +
> +#if defined(CONFIG_RANDOMIZE_BASE)
CONFIG_RANDOMIZE_BASE being enabled by itself doesn't directly imply that
kASLR has been actually really enabled during runtime. You need
to check kaslr_enabled() as well.
> + /* KASLR is enabled, disregard old_addr from user */
> + reloc->val = 0;
Is there a reason why to discard it completely? Adding kaslr_offset()
should give us the correct address, right?
Thanks,
--
Jiri Kosina
SUSE Labs
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