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| author | Eric Biggers <ebiggers@google.com> | 2019-10-21 22:49:03 +0200 |
|---|---|---|
| committer | Eric Biggers <ebiggers@google.com> | 2019-11-06 21:33:15 +0100 |
| commit | ff73c2c016f8569b728eb1e9ebfab383545e4d65 (patch) | |
| tree | 878f712c354b45c9d251da651ab4b3440e175ba2 /fs | |
| parent | docs: ioctl-number: document fscrypt ioctl numbers (diff) | |
| download | linux-ff73c2c016f8569b728eb1e9ebfab383545e4d65.tar.xz linux-ff73c2c016f8569b728eb1e9ebfab383545e4d65.zip | |
fscrypt: avoid data race on fscrypt_mode::logged_impl_name
The access to logged_impl_name is technically a data race, which tools
like KCSAN could complain about in the future. See:
https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE
Fix by using xchg(), which also ensures that only one thread does the
logging.
This also required switching from bool to int, to avoid a build error on
the RISC-V architecture which doesn't implement xchg on bytes.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/crypto/fscrypt_private.h | 2 | ||||
| -rw-r--r-- | fs/crypto/keysetup.c | 6 |
2 files changed, 3 insertions, 5 deletions
diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index dacf8fcbac3b..d9a3e8614049 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -435,7 +435,7 @@ struct fscrypt_mode { const char *cipher_str; int keysize; int ivsize; - bool logged_impl_name; + int logged_impl_name; }; static inline bool diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index b03b33643e4b..28bc2da9be3c 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -81,15 +81,13 @@ struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode, mode->cipher_str, PTR_ERR(tfm)); return tfm; } - if (unlikely(!mode->logged_impl_name)) { + if (!xchg(&mode->logged_impl_name, 1)) { /* * fscrypt performance can vary greatly depending on which * crypto algorithm implementation is used. Help people debug * performance problems by logging the ->cra_driver_name the - * first time a mode is used. Note that multiple threads can - * race here, but it doesn't really matter. + * first time a mode is used. */ - mode->logged_impl_name = true; pr_info("fscrypt: %s using implementation \"%s\"\n", mode->friendly_name, crypto_skcipher_alg(tfm)->base.cra_driver_name); |