fscrypt: don't load ->i_crypt_info before it's known to be valid

In fscrypt_set_bio_crypt_ctx(), ->i_crypt_info isn't known to be
non-NULL until we check fscrypt_inode_uses_inline_crypto().  So, load
->i_crypt_info after the check rather than before.  This makes no
difference currently, but it prevents people from introducing bugs where
the pointer is dereferenced when it may be NULL.

Suggested-by: Dave Chinner <david@fromorbit.com>
Cc: Satya Tangirala <satyat@google.com>
Link: https://lore.kernel.org/r/20200727174158.121456-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c
index dfb06375099aec30e74c672b187001d798f4d2eb..b6b8574caa13c2754b204e695d0fca19ce2cb4b7 100644 (file)
--- a/fs/crypto/inline_crypt.c
+++ b/fs/crypto/inline_crypt.c
@@ -244,11 +244,12 @@ static void fscrypt_generate_dun(const struct fscrypt_info *ci, u64 lblk_num,
 void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode,
                               u64 first_lblk, gfp_t gfp_mask)
 {
-       const struct fscrypt_info *ci = inode->i_crypt_info;
+       const struct fscrypt_info *ci;
        u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
 
        if (!fscrypt_inode_uses_inline_crypto(inode))
                return;
+       ci = inode->i_crypt_info;
 
        fscrypt_generate_dun(ci, first_lblk, dun);
        bio_crypt_set_ctx(bio, &ci->ci_enc_key.blk_key->base, dun, gfp_mask);