| Message ID | 20201111214855.428044-1-ebiggers@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v2] block/keyslot-manager: prevent crash when num_slots=1 | expand |
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?
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.
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]),