alistair23-linux/fs/crypto
Eric Biggers ab673b9874 fscrypt: use smp_load_acquire() for ->i_crypt_info
Normally smp_store_release() or cmpxchg_release() is paired with
smp_load_acquire().  Sometimes smp_load_acquire() can be replaced with
the more lightweight READ_ONCE().  However, for this to be safe, all the
published memory must only be accessed in a way that involves the
pointer itself.  This may not be the case if allocating the object also
involves initializing a static or global variable, for example.

fscrypt_info includes various sub-objects which are internal to and are
allocated by other kernel subsystems such as keyrings and crypto.  So by
using READ_ONCE() for ->i_crypt_info, we're relying on internal
implementation details of these other kernel subsystems.

Remove this fragile assumption by using smp_load_acquire() instead.

(Note: I haven't seen any real-world problems here.  This change is just
fixing the code to be guaranteed correct and less fragile.)

Fixes: e37a784d8b ("fscrypt: use READ_ONCE() to access ->i_crypt_info")
Link: https://lore.kernel.org/r/20200721225920.114347-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
2020-07-21 16:02:13 -07:00
..
bio.c fscrypt: add inline encryption support 2020-07-08 10:29:30 -07:00
crypto.c fscrypt: rename FS_KEY_DERIVATION_NONCE_SIZE 2020-07-20 17:26:33 -07:00
fname.c fscrypt: switch fscrypt_do_sha256() to use the SHA-256 library 2020-07-21 16:02:13 -07:00
fscrypt_private.h fscrypt: use smp_load_acquire() for fscrypt_prepared_key 2020-07-21 16:02:13 -07:00
hkdf.c fscrypt: use crypto_shash_tfm_digest() 2020-05-08 15:32:14 +10:00
hooks.c fscrypt: fix all kerneldoc warnings 2020-05-12 16:37:17 -07:00
inline_crypt.c fscrypt: use smp_load_acquire() for fscrypt_prepared_key 2020-07-21 16:02:13 -07:00
Kconfig fscrypt: switch fscrypt_do_sha256() to use the SHA-256 library 2020-07-21 16:02:13 -07:00
keyring.c fscrypt: use smp_load_acquire() for ->s_master_keys 2020-07-21 16:02:13 -07:00
keysetup.c fscrypt: use smp_load_acquire() for ->i_crypt_info 2020-07-21 16:02:13 -07:00
keysetup_v1.c fscrypt: rename FS_KEY_DERIVATION_NONCE_SIZE 2020-07-20 17:26:33 -07:00
Makefile fscrypt: add inline encryption support 2020-07-08 10:29:30 -07:00
policy.c fscrypt: use smp_load_acquire() for ->i_crypt_info 2020-07-21 16:02:13 -07:00