crypto: aead - Fix aead_instance struct size

The struct aead_instance is meant to extend struct crypto_instance
by incorporating the extra members of struct aead_alg.  However,
the current layout which is copied from shash/ahash does not specify
the struct fully.  In particular only aead_alg is present.

For shash/ahash this works because users there add extra headroom
to sizeof(struct crypto_instance) when allocating the instance.
Unfortunately for aead, this bit was lost when the new aead_instance
was added.

Rather than fixing it like shash/ahash, this patch simply expands
struct aead_instance to contain what is supposed to be there, i.e.,
adding struct crypto_instance.

In order to not break existing AEAD users, this is done through an
anonymous union.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/include/crypto/internal/aead.h b/include/crypto/internal/aead.h
index ba52c37b8c40e4d6c3261d2f733fc9e4b79f4979..4b2547186519f80e00729144dd8edafab238b5ef 100644 (file)
--- a/include/crypto/internal/aead.h
+++ b/include/crypto/internal/aead.h
@@ -15,12 +15,19 @@
 
 #include <crypto/aead.h>
 #include <crypto/algapi.h>
+#include <linux/stddef.h>
 #include <linux/types.h>
 
 struct rtattr;
 
 struct aead_instance {
-       struct aead_alg alg;
+       union {
+               struct {
+                       char head[offsetof(struct aead_alg, base)];
+                       struct crypto_instance base;
+               } s;
+               struct aead_alg alg;
+       };
 };
 
 struct crypto_aead_spawn {