7d206ec7a0
commit9cd1e56667upstream. Once all I/O using a blk_crypto_key has completed, filesystems can call blk_crypto_evict_key(). However, the block layer currently doesn't call blk_crypto_put_keyslot() until the request is being freed, which happens after upper layers have been told (via bio_endio()) the I/O has completed. This causes a race condition where blk_crypto_evict_key() can see 'slot_refs != 0' without there being an actual bug. This makes __blk_crypto_evict_key() hit the 'WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)' and return without doing anything, eventually causing a use-after-free in blk_crypto_reprogram_all_keys(). (This is a very rare bug and has only been seen when per-file keys are being used with fscrypt.) There are two options to fix this: either release the keyslot before bio_endio() is called on the request's last bio, or make __blk_crypto_evict_key() ignore slot_refs. Let's go with the first solution, since it preserves the ability to report bugs (via WARN_ON_ONCE) where a key is evicted while still in-use. Fixes:a892c8d52c("block: Inline encryption support for blk-mq") Cc: stable@vger.kernel.org Reviewed-by: Nathan Huckleberry <nhuck@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Eric Biggers <ebiggers@google.com> 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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.