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Message-ID: <CAGXu5jKz8YYG8V33_mBaOqfijQCBEfuOTsWXOYOO6+7fUD_=WQ@mail.gmail.com>
Date: Tue, 25 Oct 2016 11:30:18 -0700
From: Kees Cook <keescook@...omium.org>
To: Hans Liljestrand <ishkamiel@...il.com>
Cc: Colin Vidal <colin@...dal.org>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>,
Elena Reshetova <elena.reshetova@...el.com>, David Windsor <dwindsor@...il.com>
Subject: Re: [RFC v2 PATCH 13/13] lkdtm: add tests for
atomic over-/underflow
On Tue, Oct 25, 2016 at 2:11 AM, Hans Liljestrand <ishkamiel@...il.com> wrote:
> On Tue, Oct 25, 2016 at 11:04:08AM +0200, Colin Vidal wrote:
>> On Tue, 2016-10-25 at 17:56 +0900, AKASHI Takahiro wrote:
>> > On Thu, Oct 20, 2016 at 01:25:31PM +0300, Elena Reshetova wrote:
>> > >
>> > > From: Hans Liljestrand <ishkamiel@...il.com>
>> > >
>> > > This adds additional tests for modified atomic functions.
>> > >
>> > > Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
>> > > Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
>> > > Signed-off-by: David Windsor <dwindsor@...il.com>
>> > > ---
>> > > drivers/misc/lkdtm.h | 17 +++++++
>> > > drivers/misc/lkdtm_bugs.c | 122 +++++++++++++++++++++++++++++++++++++++-------
>> > > drivers/misc/lkdtm_core.c | 17 +++++++
>> > > 3 files changed, 138 insertions(+), 18 deletions(-)
>> > >
>> > > diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h
>> > > index cfa1039..224713a 100644
>> > > --- a/drivers/misc/lkdtm.h
>> > > +++ b/drivers/misc/lkdtm.h
>> > > @@ -20,7 +20,24 @@ void lkdtm_HARDLOCKUP(void);
>> > > void lkdtm_SPINLOCKUP(void);
>> > > void lkdtm_HUNG_TASK(void);
>> > > void lkdtm_ATOMIC_UNDERFLOW(void);
>> > > +void lkdtm_ATOMIC_DEC_RETURN_UNDERFLOW(void);
>> > > +void lkdtm_ATOMIC_SUB_UNDERFLOW(void);
>> > > +void lkdtm_ATOMIC_SUB_RETURN_UNDERFLOW(void);
>> > > void lkdtm_ATOMIC_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_INC_RETURN_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_ADD_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_ADD_RETURN_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_ADD_UNLESS_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_INC_AND_TEST_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_LONG_UNDERFLOW(void);
>> > > +void lkdtm_ATOMIC_LONG_DEC_RETURN_UNDERFLOW(void);
>> > > +void lkdtm_ATOMIC_LONG_SUB_UNDERFLOW(void);
>> > > +void lkdtm_ATOMIC_LONG_SUB_RETURN_UNDERFLOW(void);
>> > > +void lkdtm_ATOMIC_LONG_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_LONG_INC_RETURN_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_LONG_ADD_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_LONG_ADD_RETURN_OVERFLOW(void);
>> > > +void lkdtm_ATOMIC_LONG_SUB_AND_TEST(void);
>> > > void lkdtm_CORRUPT_LIST_ADD(void);
>> > > void lkdtm_CORRUPT_LIST_DEL(void);
>> > >
>> > > diff --git a/drivers/misc/lkdtm_bugs.c b/drivers/misc/lkdtm_bugs.c
>> > > index f336206..bd79a88 100644
>> > > --- a/drivers/misc/lkdtm_bugs.c
>> > > +++ b/drivers/misc/lkdtm_bugs.c
>> > > @@ -128,30 +128,116 @@ void lkdtm_HUNG_TASK(void)
>> > > schedule();
>> > > }
>> > >
>> > > -void lkdtm_ATOMIC_UNDERFLOW(void)
>> > > -{
>> > > - atomic_t under = ATOMIC_INIT(INT_MIN);
>> > > -
>> > > - pr_info("attempting good atomic increment\n");
>> > > - atomic_inc(&under);
>> > > - atomic_dec(&under);
>> > > -
>> > > - pr_info("attempting bad atomic underflow\n");
>> > > - atomic_dec(&under);
>> > > +#define ATOMIC_LKDTM_MIN(tag,fun) void lkdtm_ATOMIC_##tag(void) \
>> > > +{ \
>> > > + atomic_t atomic = ATOMIC_INIT(INT_MIN); \
>> > > + \
>> > > + pr_info("attempting good atomic_" #fun "\n"); \
>> > > + atomic_inc(&atomic); \
>> > > + TEST_FUNC(&atomic); \
>> > > + \
>> > > + pr_info("attempting bad atomic_" #fun "\n"); \
>> > > + TEST_FUNC(&atomic); \
>> > > }
>> > >
>> > > -void lkdtm_ATOMIC_OVERFLOW(void)
>> > > -{
>> > > - atomic_t over = ATOMIC_INIT(INT_MAX);
>> > > +#define ATOMIC_LKDTM_MAX(tag,fun,...) \
>> > > +void lkdtm_ATOMIC_##tag(void) \
>> > > +{ \
>> > > + atomic_t atomic = ATOMIC_INIT(INT_MAX); \
>> > > + \
>> > > + pr_info("attempting good atomic_" #fun "\n"); \
>> > > + atomic_dec(&atomic); \
>> > > + TEST_FUNC(&atomic); \
>> > > + \
>> > > + pr_info("attempting bad atomic_" #fun "\n"); \
>> > > + TEST_FUNC(&atomic); \
>> > > +}
>> > >
>> > > - pr_info("attempting good atomic decrement\n");
>> > > - atomic_dec(&over);
>> > > - atomic_inc(&over);
>> > > +#define ATOMIC_LKDTM_LONG_MIN(tag,fun,...) \
>> > > +void lkdtm_ATOMIC_LONG_##tag(void) \
>> > > +{ \
>> > > + atomic_long_t atomic = ATOMIC_LONG_INIT(LONG_MIN); \
>> > > + \
>> > > + pr_info("attempting good atomic_long_" #fun "\n"); \
>> > > + atomic_long_inc(&atomic); \
>> > > + TEST_FUNC(&atomic); \
>> > > + \
>> > > + pr_info("attempting bad atomic_long_" #fun "\n"); \
>> > > + TEST_FUNC(&atomic); \
>> > > +}
>> > >
>> > > - pr_info("attempting bad atomic overflow\n");
>> > > - atomic_inc(&over);
>> > > +#define ATOMIC_LKDTM_LONG_MAX(tag,fun,...) \
>> > > +void lkdtm_ATOMIC_LONG_##tag(void) \
>> > > +{ \
>> > > + atomic_long_t atomic = ATOMIC_LONG_INIT(LONG_MAX); \
>> > > + \
>> > > + pr_info("attempting good atomic_long_" #fun "\n"); \
>> > > + atomic_long_dec(&atomic); \
>> > > + TEST_FUNC(&atomic); \
>> > > + \
>> > > + pr_info("attempting bad atomic_long_" #fun "\n"); \
>> > > + TEST_FUNC(&atomic); \
>> > > }
>> > >
>> > > +#define TEST_FUNC(x) atomic_dec(x)
>> > > +ATOMIC_LKDTM_MIN(UNDERFLOW,dec)
>> > > +#undef TEST_FUNC
>> > > +#define TEST_FUNC(x) atomic_dec_return(x)
>> > > +ATOMIC_LKDTM_MIN(DEC_RETURN_UNDERFLOW,dec_return);
>> > > +#undef TEST_FUNC
>> > > +#define TEST_FUNC(x) atomic_sub(1,x)
>> > > +ATOMIC_LKDTM_MIN(SUB_UNDERFLOW,sub);
>> > > +#undef TEST_FUNC
>> > > +#define TEST_FUNC(x) atomic_sub_return(1,x);
>> > > +ATOMIC_LKDTM_MIN(SUB_RETURN_UNDERFLOW,sub_return);
>> > > +#undef TEST_FUNC
>> > > +#define TEST_FUNC(x) atomic_inc(x);
>> > > +ATOMIC_LKDTM_MAX(OVERFLOW,inc);
>> > > +#undef TEST_FUNC
>> > > +#define TEST_FUNC(x) atomic_inc_return(x);
>> > > +ATOMIC_LKDTM_MAX(INC_RETURN_OVERFLOW,inc_return);
>> >
>> > Please note that this definition causes a compiler warning:
>> > /home/akashi/arm/armv8/linaro/linux-aarch64/drivers/misc/lkdtm_bugs.c: In function 'lkdtm_ATOMIC_INC_AND_TEST_OVERFLOW':
>> > /home/akashi/arm/armv8/linaro/linux-aarch64/arch/arm64/include/asm/atomic.h:222:55: warning: value computed is not used [-Wunused-value]
>> > #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
>> > ^
>> > /home/akashi/arm/armv8/linaro/linux-aarch64/drivers/misc/lkdtm_bugs.c:204:22: note: in expansion of macro 'atomic_inc_and_test'
>> > #define TEST_FUNC(x) atomic_inc_and_test(x);
>> >
>>
>> There is the same issue with arm.
>>
>> Thanks,
>>
>> Colin
>>
>
> Yes, thanks! Looks like the same issue should be on x86, not sure why I didn't
> catch that. Will fix.
I've got a clean-up for the macros too, I'll send that out in a minute here...
-Kees
--
Kees Cook
Nexus Security
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