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authorEric Biggers <ebiggers@google.com>2020-11-12 00:48:55 +0300
committerJens Axboe <axboe@kernel.dk>2020-11-20 21:52:52 +0300
commit47a846536e1bf62626f1c0d8488f3718ce5f8296 (patch)
treea26fb9f3bd73eb3e521ec9fc76af8727629f7fe1 /block
parent45f703a0d4b87f940ea150367dc4f4a9c06fa868 (diff)
downloadlinux-47a846536e1bf62626f1c0d8488f3718ce5f8296.tar.xz
block/keyslot-manager: prevent crash when num_slots=1
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>
Diffstat (limited to 'block')
-rw-r--r--block/keyslot-manager.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/block/keyslot-manager.c b/block/keyslot-manager.c
index 35abcb1ec051..86f8195d8039 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]),