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| author |   Eric Biggers <ebiggers@google.com> | 2019-04-11 14:32:15 -0700 |
|---|---|---|
| committer |   Theodore Ts'o <tytso@mit.edu> | 2019-04-16 18:57:09 -0400 |
| commit | e37a784d8b6a1e726de5ddc7b4809c086a08db09 (patch) | |
| tree | 965d40cec69107aba4324f72db93d896b12d0737 /fs/crypto/fname.c | |
| parent | fscrypt: remove WARN_ON_ONCE() when decryption fails (diff) | |
| download | wireguard-linux-e37a784d8b6a1e726de5ddc7b4809c086a08db09.tar.xz wireguard-linux-e37a784d8b6a1e726de5ddc7b4809c086a08db09.zip | |
fscrypt: use READ_ONCE() to access ->i_crypt_info
->i_crypt_info starts out NULL and may later be locklessly set to a
non-NULL value by the cmpxchg() in fscrypt_get_encryption_info().
But ->i_crypt_info is used directly, which technically is incorrect.
It's a data race, and it doesn't include the data dependency barrier
needed to safely dereference the pointer on at least one architecture.
Fix this by using READ_ONCE() instead. Note: we don't need to use
smp_load_acquire(), since dereferencing the pointer only requires a data
dependency barrier, which is already included in READ_ONCE(). We also
don't need READ_ONCE() in places where ->i_crypt_info is unconditionally
dereferenced, since it must have already been checked.
Also downgrade the cmpxchg() to cmpxchg_release(), since RELEASE
semantics are sufficient on the write side.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/crypto/fname.c')
| -rw-r--r-- | fs/crypto/fname.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index 7ff40a73dbec..050384c79f40 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -269,7 +269,7 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, if (iname->len < FS_CRYPTO_BLOCK_SIZE) return -EUCLEAN; - if (inode->i_crypt_info) + if (fscrypt_has_encryption_key(inode)) return fname_decrypt(inode, iname, oname); if (iname->len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE) { @@ -336,7 +336,7 @@ int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, if (ret) return ret; - if (dir->i_crypt_info) { + if (fscrypt_has_encryption_key(dir)) { if (!fscrypt_fname_encrypted_size(dir, iname->len, dir->i_sb->s_cop->max_namelen, &fname->crypto_buf.len)) |