Eric Biggers 5bb4005fb6 blk-crypto: make blk_crypto_evict_key() more robust
commit 5c7cb94452901a93e90c2230632e2c12a681bc92 upstream.

If blk_crypto_evict_key() sees that the key is still in-use (due to a
bug) or that ->keyslot_evict failed, it currently just returns while
leaving the key linked into the keyslot management structures.

However, blk_crypto_evict_key() is only called in contexts such as inode
eviction where failure is not an option.  So actually the caller
proceeds with freeing the blk_crypto_key regardless of the return value
of blk_crypto_evict_key().

These two assumptions don't match, and the result is that there can be a
use-after-free in blk_crypto_reprogram_all_keys() after one of these
errors occurs.  (Note, these errors *shouldn't* happen; we're just
talking about what happens if they do anyway.)

Fix this by making blk_crypto_evict_key() unlink the key from the
keyslot management structures even on failure.

Also improve some comments.

Fixes: 1b2628397058 ("block: Keyslot Manager for Inline Encryption")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230315183907.53675-2-ebiggers@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-05-11 23:00:16 +09:00
..
2021-06-17 15:51:20 +02:00
2020-03-17 20:55:21 +01:00
2021-09-14 00:22:15 -04:00
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