* [PATCH] block/keyslot-manager: prevent crash when num_slots=1
@ 2020-11-11 2:14 Eric Biggers
2020-11-11 9:23 ` Christoph Hellwig
2020-11-11 9:49 ` Satya Tangirala
0 siblings, 2 replies; 7+ messages in thread
From: Eric Biggers @ 2020-11-11 2:14 UTC (permalink / raw)
To: linux-block, Jens Axboe; +Cc: linux-fscrypt, Satya Tangirala
From: Eric Biggers <ebiggers@google.com>
If there is only one keyslot, then blk_ksm_init() computes
slot_hashtable_size=1 and log_slot_ht_size=0. This causes
blk_ksm_find_keyslot() to crash later because it uses
hash_ptr(key, log_slot_ht_size) to find the hash bucket containing the
key, and hash_ptr() doesn't support the bits == 0 case.
Fix this by making the hash table always have at least 2 buckets.
Tested by running:
kvm-xfstests -c ext4 -g encrypt -m inlinecrypt \
-o blk-crypto-fallback.num_keyslots=1
Fixes: 1b2628397058 ("block: Keyslot Manager for Inline Encryption")
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
block/keyslot-manager.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/block/keyslot-manager.c b/block/keyslot-manager.c
index 35abcb1ec051d..0a5b2772324ad 100644
--- a/block/keyslot-manager.c
+++ b/block/keyslot-manager.c
@@ -103,6 +103,13 @@ int blk_ksm_init(struct blk_keyslot_manager *ksm, unsigned int num_slots)
spin_lock_init(&ksm->idle_slots_lock);
slot_hashtable_size = roundup_pow_of_two(num_slots);
+
+ /*
+ * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
+ * buckets. This only makes a difference when there is only 1 keyslot.
+ */
+ slot_hashtable_size = max(slot_hashtable_size, 2U);
+
ksm->log_slot_ht_size = ilog2(slot_hashtable_size);
ksm->slot_hashtable = kvmalloc_array(slot_hashtable_size,
sizeof(ksm->slot_hashtable[0]),
base-commit: f8394f232b1eab649ce2df5c5f15b0e528c92091
--
2.29.2
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] block/keyslot-manager: prevent crash when num_slots=1
2020-11-11 2:14 [PATCH] block/keyslot-manager: prevent crash when num_slots=1 Eric Biggers
@ 2020-11-11 9:23 ` Christoph Hellwig
2020-11-11 9:45 ` Satya Tangirala
2020-11-11 9:49 ` Satya Tangirala
1 sibling, 1 reply; 7+ messages in thread
From: Christoph Hellwig @ 2020-11-11 9:23 UTC (permalink / raw)
To: Eric Biggers; +Cc: linux-block, Jens Axboe, linux-fscrypt, Satya Tangirala
On Tue, Nov 10, 2020 at 06:14:27PM -0800, Eric Biggers wrote:
> + * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
> + * buckets. This only makes a difference when there is only 1 keyslot.
> + */
> + slot_hashtable_size = max(slot_hashtable_size, 2U);
shouldn't this be a min()?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] block/keyslot-manager: prevent crash when num_slots=1
2020-11-11 9:23 ` Christoph Hellwig
@ 2020-11-11 9:45 ` Satya Tangirala
2020-11-11 19:25 ` Eric Biggers
2020-11-16 16:34 ` Christoph Hellwig
0 siblings, 2 replies; 7+ messages in thread
From: Satya Tangirala @ 2020-11-11 9:45 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: Eric Biggers, linux-block, Jens Axboe, linux-fscrypt
On Wed, Nov 11, 2020 at 09:23:05AM +0000, Christoph Hellwig wrote:
> On Tue, Nov 10, 2020 at 06:14:27PM -0800, Eric Biggers wrote:
> > + * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
> > + * buckets. This only makes a difference when there is only 1 keyslot.
> > + */
> > + slot_hashtable_size = max(slot_hashtable_size, 2U);
>
> shouldn't this be a min()?
I think it should be max(), since we want whichever is larger between 2
and the original slot_hashtable_size :)
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] block/keyslot-manager: prevent crash when num_slots=1
2020-11-11 9:45 ` Satya Tangirala
@ 2020-11-11 19:25 ` Eric Biggers
2020-11-11 21:50 ` Eric Biggers
2020-11-16 16:34 ` Christoph Hellwig
1 sibling, 1 reply; 7+ messages in thread
From: Eric Biggers @ 2020-11-11 19:25 UTC (permalink / raw)
To: Satya Tangirala; +Cc: Christoph Hellwig, linux-block, Jens Axboe, linux-fscrypt
On Wed, Nov 11, 2020 at 09:45:38AM +0000, Satya Tangirala wrote:
> On Wed, Nov 11, 2020 at 09:23:05AM +0000, Christoph Hellwig wrote:
> > On Tue, Nov 10, 2020 at 06:14:27PM -0800, Eric Biggers wrote:
> > > + * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
> > > + * buckets. This only makes a difference when there is only 1 keyslot.
> > > + */
> > > + slot_hashtable_size = max(slot_hashtable_size, 2U);
> >
> > shouldn't this be a min()?
> I think it should be max(), since we want whichever is larger between 2
> and the original slot_hashtable_size :)
max() is correct. I could just open-code it, if that would make it clearer:
/*
* hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
* buckets. This only makes a difference when there is only 1 keyslot.
*/
if (slot_hashtable_size < 2)
slot_hashtable_size = 2;
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] block/keyslot-manager: prevent crash when num_slots=1
2020-11-11 19:25 ` Eric Biggers
@ 2020-11-11 21:50 ` Eric Biggers
0 siblings, 0 replies; 7+ messages in thread
From: Eric Biggers @ 2020-11-11 21:50 UTC (permalink / raw)
To: Satya Tangirala; +Cc: Christoph Hellwig, linux-block, Jens Axboe, linux-fscrypt
On Wed, Nov 11, 2020 at 11:25:39AM -0800, Eric Biggers wrote:
> On Wed, Nov 11, 2020 at 09:45:38AM +0000, Satya Tangirala wrote:
> > On Wed, Nov 11, 2020 at 09:23:05AM +0000, Christoph Hellwig wrote:
> > > On Tue, Nov 10, 2020 at 06:14:27PM -0800, Eric Biggers wrote:
> > > > + * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
> > > > + * buckets. This only makes a difference when there is only 1 keyslot.
> > > > + */
> > > > + slot_hashtable_size = max(slot_hashtable_size, 2U);
> > >
> > > shouldn't this be a min()?
> > I think it should be max(), since we want whichever is larger between 2
> > and the original slot_hashtable_size :)
>
> max() is correct. I could just open-code it, if that would make it clearer:
>
> /*
> * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
> * buckets. This only makes a difference when there is only 1 keyslot.
> */
> if (slot_hashtable_size < 2)
> slot_hashtable_size = 2;
I sent out v2 with the above.
- Eric
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] block/keyslot-manager: prevent crash when num_slots=1
2020-11-11 9:45 ` Satya Tangirala
2020-11-11 19:25 ` Eric Biggers
@ 2020-11-16 16:34 ` Christoph Hellwig
1 sibling, 0 replies; 7+ messages in thread
From: Christoph Hellwig @ 2020-11-16 16:34 UTC (permalink / raw)
To: Satya Tangirala
Cc: Christoph Hellwig, Eric Biggers, linux-block, Jens Axboe, linux-fscrypt
On Wed, Nov 11, 2020 at 09:45:38AM +0000, Satya Tangirala wrote:
> On Wed, Nov 11, 2020 at 09:23:05AM +0000, Christoph Hellwig wrote:
> > On Tue, Nov 10, 2020 at 06:14:27PM -0800, Eric Biggers wrote:
> > > + * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
> > > + * buckets. This only makes a difference when there is only 1 keyslot.
> > > + */
> > > + slot_hashtable_size = max(slot_hashtable_size, 2U);
> >
> > shouldn't this be a min()?
> I think it should be max(), since we want whichever is larger between 2
> and the original slot_hashtable_size :)
Yes, of course. Sorry for the noise.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] block/keyslot-manager: prevent crash when num_slots=1
2020-11-11 2:14 [PATCH] block/keyslot-manager: prevent crash when num_slots=1 Eric Biggers
2020-11-11 9:23 ` Christoph Hellwig
@ 2020-11-11 9:49 ` Satya Tangirala
1 sibling, 0 replies; 7+ messages in thread
From: Satya Tangirala @ 2020-11-11 9:49 UTC (permalink / raw)
To: Eric Biggers; +Cc: linux-block, Jens Axboe, linux-fscrypt
On Tue, Nov 10, 2020 at 06:14:27PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> If there is only one keyslot, then blk_ksm_init() computes
> slot_hashtable_size=1 and log_slot_ht_size=0. This causes
> blk_ksm_find_keyslot() to crash later because it uses
> hash_ptr(key, log_slot_ht_size) to find the hash bucket containing the
> key, and hash_ptr() doesn't support the bits == 0 case.
>
> Fix this by making the hash table always have at least 2 buckets.
>
> Tested by running:
>
> kvm-xfstests -c ext4 -g encrypt -m inlinecrypt \
> -o blk-crypto-fallback.num_keyslots=1
>
> Fixes: 1b2628397058 ("block: Keyslot Manager for Inline Encryption")
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
> block/keyslot-manager.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/block/keyslot-manager.c b/block/keyslot-manager.c
> index 35abcb1ec051d..0a5b2772324ad 100644
> --- a/block/keyslot-manager.c
> +++ b/block/keyslot-manager.c
> @@ -103,6 +103,13 @@ int blk_ksm_init(struct blk_keyslot_manager *ksm, unsigned int num_slots)
> spin_lock_init(&ksm->idle_slots_lock);
>
> slot_hashtable_size = roundup_pow_of_two(num_slots);
> +
> + /*
> + * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
> + * buckets. This only makes a difference when there is only 1 keyslot.
> + */
> + slot_hashtable_size = max(slot_hashtable_size, 2U);
> +
> ksm->log_slot_ht_size = ilog2(slot_hashtable_size);
> ksm->slot_hashtable = kvmalloc_array(slot_hashtable_size,
> sizeof(ksm->slot_hashtable[0]),
>
> base-commit: f8394f232b1eab649ce2df5c5f15b0e528c92091
> --
> 2.29.2
>
Looks good to me. Please feel free to add
Reviewed-by: Satya Tangirala <satyat@google.com>
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-11-16 16:34 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-11 2:14 [PATCH] block/keyslot-manager: prevent crash when num_slots=1 Eric Biggers
2020-11-11 9:23 ` Christoph Hellwig
2020-11-11 9:45 ` Satya Tangirala
2020-11-11 19:25 ` Eric Biggers
2020-11-11 21:50 ` Eric Biggers
2020-11-16 16:34 ` Christoph Hellwig
2020-11-11 9:49 ` Satya Tangirala
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.