| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.9 092/152] block/keyslot-manager: prevent crash when num_slots=1 | Date | Tue, 1 Dec 2020 09:53:27 +0100 |
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From: Eric Biggers <ebiggers@google.com>
[ Upstream commit 47a846536e1bf62626f1c0d8488f3718ce5f8296 ]
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> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> --- 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]), -- 2.27.0
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