* [PATCH v2] block/keyslot-manager: prevent crash when num_slots=1
@ 2020-11-11 21:48 Eric Biggers
2020-11-20 18:49 ` Eric Biggers
2020-11-20 18:53 ` Jens Axboe
0 siblings, 2 replies; 3+ messages in thread
From: Eric Biggers @ 2020-11-11 21:48 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..86f8195d8039e 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.
+ */
+ if (slot_hashtable_size < 2)
+ slot_hashtable_size = 2;
+
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] 3+ messages in thread
* Re: [PATCH v2] block/keyslot-manager: prevent crash when num_slots=1
2020-11-11 21:48 [PATCH v2] block/keyslot-manager: prevent crash when num_slots=1 Eric Biggers
@ 2020-11-20 18:49 ` Eric Biggers
2020-11-20 18:53 ` Jens Axboe
1 sibling, 0 replies; 3+ messages in thread
From: Eric Biggers @ 2020-11-20 18:49 UTC (permalink / raw)
To: linux-block, Jens Axboe; +Cc: linux-fscrypt, Satya Tangirala
On Wed, Nov 11, 2020 at 01:48:55PM -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..86f8195d8039e 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.
> + */
> + if (slot_hashtable_size < 2)
> + slot_hashtable_size = 2;
> +
> ksm->log_slot_ht_size = ilog2(slot_hashtable_size);
> ksm->slot_hashtable = kvmalloc_array(slot_hashtable_size,
> sizeof(ksm->slot_hashtable[0]),
>
Ping?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] block/keyslot-manager: prevent crash when num_slots=1
2020-11-11 21:48 [PATCH v2] block/keyslot-manager: prevent crash when num_slots=1 Eric Biggers
2020-11-20 18:49 ` Eric Biggers
@ 2020-11-20 18:53 ` Jens Axboe
1 sibling, 0 replies; 3+ messages in thread
From: Jens Axboe @ 2020-11-20 18:53 UTC (permalink / raw)
To: Eric Biggers, linux-block; +Cc: linux-fscrypt, Satya Tangirala
On 11/11/20 2:48 PM, 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
Applied for 5.10, thanks.
--
Jens Axboe
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-11-11 21:48 [PATCH v2] block/keyslot-manager: prevent crash when num_slots=1 Eric Biggers
2020-11-20 18:49 ` Eric Biggers
2020-11-20 18:53 ` Jens Axboe
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