Messages in this thread | | | Date | Wed, 4 Nov 2015 10:44:55 +0100 (CET) | From | Jiri Kosina <> | Subject | Re: [PATCH] livepatch: x86: bugfix about kASLR |
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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. <cbay@alwaysdata.com> > Signed-off-by: Zhou Chengming <zhouchengming1@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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