Re: [PATCH] crypto: DRBG - always try to free Jitter RNG instance
Am Mittwoch, 3. Juni 2020, 13:09:19 CEST schrieb Dan Carpenter:
Hi Dan,
> On Wed, Jun 03, 2020 at 10:08:56AM +0200, Stephan Müller wrote:
> > The Jitter RNG is unconditionally allocated as a seed source follwoing
> > the patch 97f2650e5040. Thus, the instance must always be deallocated.
> >
> > Reported-by: syzbot+2e635807decef724a...@syzkaller.appspotmail.com
> > Fixes: 97f2650e5040 ("crypto: drbg - always seeded with SP800-90B ...")
> > Signed-off-by: Stephan Mueller
> > ---
> >
> > crypto/drbg.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/crypto/drbg.c b/crypto/drbg.c
> > index 37526eb8c5d5..33d28016da2d 100644
> > --- a/crypto/drbg.c
> > +++ b/crypto/drbg.c
> > @@ -1631,6 +1631,9 @@ static int drbg_uninstantiate(struct drbg_state
> > *drbg)>
> > if (drbg->random_ready.func) {
> >
> > del_random_ready_callback(>random_ready);
> > cancel_work_sync(>seed_work);
> >
> > + }
> > +
> > + if (drbg->jent) {
> >
> > crypto_free_rng(drbg->jent);
> > drbg->jent = NULL;
> >
> > }
>
> free_everything functions never work. For example, "drbg->jent" can be
> an error pointer at this point.
>
> crypto/drbg.c
> 1577 if (!drbg->core) {
> 1578 drbg->core = _cores[coreref];
> 1579 drbg->pr = pr;
> 1580 drbg->seeded = false;
> 1581 drbg->reseed_threshold = drbg_max_requests(drbg);
> 1582
> 1583 ret = drbg_alloc_state(drbg);
> 1584 if (ret)
> 1585 goto unlock;
> 1586
> 1587 ret = drbg_prepare_hrng(drbg);
> 1588 if (ret)
> 1589 goto free_everything;
>
> If we hit two failures inside drbg_prepare_hrng() then "drbg->jent" can
> be an error pointer.
>
> 1590
> 1591 if (IS_ERR(drbg->jent)) {
> 1592 ret = PTR_ERR(drbg->jent);
> 1593 drbg->jent = NULL;
> 1594 if (fips_enabled || ret != -ENOENT)
> 1595 goto free_everything;
> 1596 pr_info("DRBG: Continuing without Jitter
> RNG\n"); 1597 }
> 1598
> 1599 reseed = false;
> 1600 }
> 1601
> 1602 ret = drbg_seed(drbg, pers, reseed);
> 1603
> 1604 if (ret && !reseed)
> 1605 goto free_everything;
> 1606
> 1607 mutex_unlock(>drbg_mutex);
> 1608 return ret;
> 1609
> 1610 unlock:
> 1611 mutex_unlock(>drbg_mutex);
> 1612 return ret;
> 1613
> 1614 free_everything:
> 1615 mutex_unlock(>drbg_mutex);
> 1616 drbg_uninstantiate(drbg);
>
> Leading to an Oops.
Thanks a lot for the hint - a version 2 should come shortly.
>
> 1617 return ret;
> 1618 }
>
> regards,
> dan carpenter
Ciao
Stephan
Re: [PATCH] crypto: DRBG - always try to free Jitter RNG instance
On Wed, Jun 03, 2020 at 10:08:56AM +0200, Stephan Müller wrote:
> The Jitter RNG is unconditionally allocated as a seed source follwoing
> the patch 97f2650e5040. Thus, the instance must always be deallocated.
>
> Reported-by: syzbot+2e635807decef724a...@syzkaller.appspotmail.com
> Fixes: 97f2650e5040 ("crypto: drbg - always seeded with SP800-90B ...")
> Signed-off-by: Stephan Mueller
> ---
> crypto/drbg.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/crypto/drbg.c b/crypto/drbg.c
> index 37526eb8c5d5..33d28016da2d 100644
> --- a/crypto/drbg.c
> +++ b/crypto/drbg.c
> @@ -1631,6 +1631,9 @@ static int drbg_uninstantiate(struct drbg_state *drbg)
> if (drbg->random_ready.func) {
> del_random_ready_callback(>random_ready);
> cancel_work_sync(>seed_work);
> + }
> +
> + if (drbg->jent) {
> crypto_free_rng(drbg->jent);
> drbg->jent = NULL;
> }
free_everything functions never work. For example, "drbg->jent" can be
an error pointer at this point.
crypto/drbg.c
1577 if (!drbg->core) {
1578 drbg->core = _cores[coreref];
1579 drbg->pr = pr;
1580 drbg->seeded = false;
1581 drbg->reseed_threshold = drbg_max_requests(drbg);
1582
1583 ret = drbg_alloc_state(drbg);
1584 if (ret)
1585 goto unlock;
1586
1587 ret = drbg_prepare_hrng(drbg);
1588 if (ret)
1589 goto free_everything;
If we hit two failures inside drbg_prepare_hrng() then "drbg->jent" can
be an error pointer.
1590
1591 if (IS_ERR(drbg->jent)) {
1592 ret = PTR_ERR(drbg->jent);
1593 drbg->jent = NULL;
1594 if (fips_enabled || ret != -ENOENT)
1595 goto free_everything;
1596 pr_info("DRBG: Continuing without Jitter
RNG\n");
1597 }
1598
1599 reseed = false;
1600 }
1601
1602 ret = drbg_seed(drbg, pers, reseed);
1603
1604 if (ret && !reseed)
1605 goto free_everything;
1606
1607 mutex_unlock(>drbg_mutex);
1608 return ret;
1609
1610 unlock:
1611 mutex_unlock(>drbg_mutex);
1612 return ret;
1613
1614 free_everything:
1615 mutex_unlock(>drbg_mutex);
1616 drbg_uninstantiate(drbg);
Leading to an Oops.
1617 return ret;
1618 }
regards,
dan carpenter
[PATCH] crypto: DRBG - always try to free Jitter RNG instance
The Jitter RNG is unconditionally allocated as a seed source follwoing
the patch 97f2650e5040. Thus, the instance must always be deallocated.
Reported-by: syzbot+2e635807decef724a...@syzkaller.appspotmail.com
Fixes: 97f2650e5040 ("crypto: drbg - always seeded with SP800-90B ...")
Signed-off-by: Stephan Mueller
---
crypto/drbg.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/crypto/drbg.c b/crypto/drbg.c
index 37526eb8c5d5..33d28016da2d 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1631,6 +1631,9 @@ static int drbg_uninstantiate(struct drbg_state *drbg)
if (drbg->random_ready.func) {
del_random_ready_callback(>random_ready);
cancel_work_sync(>seed_work);
+ }
+
+ if (drbg->jent) {
crypto_free_rng(drbg->jent);
drbg->jent = NULL;
}
--
2.26.2
