diff options
| author | Eric Biggers <ebiggers@google.com> | 2020-07-21 15:59:19 -0700 |
|---|---|---|
| committer | Eric Biggers <ebiggers@google.com> | 2020-07-21 16:02:13 -0700 |
| commit | ab673b987488c4fab7a0bc4824a48211f9d910e3 (patch) | |
| tree | 16ec1d6324aa8c0fe60f3d5f45f35b65de43f2ae /fs/crypto/policy.c | |
| parent | 777afe4e68d7ac37711d36098bea65650ec305a0 (diff) | |
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: e37a784d8b6a ("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>
Diffstat (limited to 'fs/crypto/policy.c')
| -rw-r--r-- | fs/crypto/policy.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 8e667aadf271..2d73fd39ad96 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -352,7 +352,7 @@ static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy) union fscrypt_context ctx; int ret; - ci = READ_ONCE(inode->i_crypt_info); + ci = fscrypt_get_info(inode); if (ci) { /* key available, use the cached policy */ *policy = ci->ci_policy; @@ -641,7 +641,7 @@ int fscrypt_inherit_context(struct inode *parent, struct inode *child, if (res < 0) return res; - ci = READ_ONCE(parent->i_crypt_info); + ci = fscrypt_get_info(parent); if (ci == NULL) return -ENOKEY; |