On Mon, Jul 10, 2017 at 08:10:02AM -0400, Sowmini Varadhan wrote:
> The reason that the WARN_ON is triggered is that af_alg_accept() calls
> sock_init_data() which does 
>    2636         if (sock) {
>     :
>    2639                 sock->sk        =       sk;

Oh yes.  This started out with just sock_init_data which would
not have triggered your warning.  Then someone came along and
added sock_graft which basically duplicates work already done in

In fact the reason they wanted sock_graft was purely to call
security_sock_graft to initialise some SELinux state.  So we
could avoid your warning by calling that directly.

crypto: af_alg - Avoid sock_graft call warning

The newly added sock_graft warning triggers in af_alg_accept.
It's harmless as we're essentially doing sock->sk = sock->sk.

The sock_graft call is actually redundant because all the work
it does is subsumed by sock_init_data.  However, it was added
to placate SELinux as it uses it to initialise its internal state.

This patch avoisd the warning by making the SELinux call directly.

Reported-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Herbert Xu <herb...@gondor.apana.org.au>

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 3556d8e..92a3d54 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -287,7 +287,7 @@ int af_alg_accept(struct sock *sk, struct socket *newsock, 
bool kern)
                goto unlock;
        sock_init_data(newsock, sk2);
-       sock_graft(sk2, newsock);
+       security_sock_graft(sk2, newsock);
        security_sk_clone(sk, sk2);
        err = type->accept(ask->private, sk2);
Email: Herbert Xu <herb...@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

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