Messages in this thread | | | Subject | Re: [PATCH 6/7] lkdtm: crash on overwriting protected pmalloc var | From | J Freyensee <> | Date | Tue, 6 Mar 2018 09:20:04 -0800 |
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On 2/28/18 12:06 PM, Igor Stoppa wrote: > Verify that pmalloc read-only protection is in place: trying to > overwrite a protected variable will crash the kernel. > > Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com> > --- > drivers/misc/lkdtm.h | 1 + > drivers/misc/lkdtm_core.c | 3 +++ > drivers/misc/lkdtm_perms.c | 28 ++++++++++++++++++++++++++++ > 3 files changed, 32 insertions(+) > > diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h > index 9e513dcfd809..dcda3ae76ceb 100644 > --- a/drivers/misc/lkdtm.h > +++ b/drivers/misc/lkdtm.h > @@ -38,6 +38,7 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void); > void __init lkdtm_perms_init(void); > void lkdtm_WRITE_RO(void); > void lkdtm_WRITE_RO_AFTER_INIT(void); > +void lkdtm_WRITE_RO_PMALLOC(void);
Does this need some sort of #ifdef too?
> void lkdtm_WRITE_KERN(void); > void lkdtm_EXEC_DATA(void); > void lkdtm_EXEC_STACK(void); > diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c > index 2154d1bfd18b..c9fd42bda6ee 100644 > --- a/drivers/misc/lkdtm_core.c > +++ b/drivers/misc/lkdtm_core.c > @@ -155,6 +155,9 @@ static const struct crashtype crashtypes[] = { > CRASHTYPE(ACCESS_USERSPACE), > CRASHTYPE(WRITE_RO), > CRASHTYPE(WRITE_RO_AFTER_INIT), > +#ifdef CONFIG_PROTECTABLE_MEMORY > + CRASHTYPE(WRITE_RO_PMALLOC), > +#endif > CRASHTYPE(WRITE_KERN), > CRASHTYPE(REFCOUNT_INC_OVERFLOW), > CRASHTYPE(REFCOUNT_ADD_OVERFLOW), > diff --git a/drivers/misc/lkdtm_perms.c b/drivers/misc/lkdtm_perms.c > index 53b85c9d16b8..0ac9023fd2b0 100644 > --- a/drivers/misc/lkdtm_perms.c > +++ b/drivers/misc/lkdtm_perms.c > @@ -9,6 +9,7 @@ > #include <linux/vmalloc.h> > #include <linux/mman.h> > #include <linux/uaccess.h> > +#include <linux/pmalloc.h> > #include <asm/cacheflush.h> > > /* Whether or not to fill the target memory area with do_nothing(). */ > @@ -104,6 +105,33 @@ void lkdtm_WRITE_RO_AFTER_INIT(void) > *ptr ^= 0xabcd1234; > } > > +#ifdef CONFIG_PROTECTABLE_MEMORY > +void lkdtm_WRITE_RO_PMALLOC(void) > +{ > + struct gen_pool *pool; > + int *i; > + > + pool = pmalloc_create_pool("pool", 0); > + if (unlikely(!pool)) { > + pr_info("Failed preparing pool for pmalloc test."); > + return; > + } > + > + i = (int *)pmalloc(pool, sizeof(int), GFP_KERNEL); > + if (unlikely(!i)) { > + pr_info("Failed allocating memory for pmalloc test."); > + pmalloc_destroy_pool(pool); > + return; > + } > + > + *i = INT_MAX; > + pmalloc_protect_pool(pool); > + > + pr_info("attempting bad pmalloc write at %p\n", i); > + *i = 0;
OK, now I'm on the right version of this patch series, same comment applies. I don't get the local *i assignment at the end of the function, but seems harmless.
Except the two minor comments, otherwise, Reviewed-by: Jay Freyensee <why2jjj.linux@gmail.com>
> +} > +#endif > + > void lkdtm_WRITE_KERN(void) > { > size_t size;
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