[PATCH] svcrpc: fix handling of garbage args

["J. Bruce Fields" <bfields@fieldses.org>]

From: J. Bruce Fields <bfields@citi.umich.edu>

To return garbage_args, the accept_stat must be 0, and we must have a
verifier.  So we shouldn't be resetting the write pointer as we reject
the call.

Also, we must add the two placeholder words here regardless of success
of the unwrap, to ensure the output buffer is left in a consistent state
for svcauth_gss_release().

This fixes a BUG() in svcauth_gss.c:svcauth_gss_release().

Thanks to Aime Le Rouzic for bug report, debugging help, and testing.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Tested-by: Aime Le Rouzic <aime.le-rouzic at bull.net>
---
 net/sunrpc/auth_gss/svcauth_gss.c |   12 +++++-------
 1 files changed, 5 insertions(+), 7 deletions(-)

This is a bugfix appropriate for 2.6.26, and the same patch is also
available from the "for-2.6.26" branch at

	git://linux-nfs.org/~bfields/linux.git for-2.6.26

--b.

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 5905d56..81ae3d6 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -1144,20 +1144,20 @@ svcauth_gss_accept(struct svc_rqst *rqstp, __be32 *authp)
 		case RPC_GSS_SVC_NONE:
 			break;
 		case RPC_GSS_SVC_INTEGRITY:
+			/* placeholders for length and seq. number: */
+			svc_putnl(resv, 0);
+			svc_putnl(resv, 0);
 			if (unwrap_integ_data(&rqstp->rq_arg,
 					gc->gc_seq, rsci->mechctx))
 				goto garbage_args;
+			break;
+		case RPC_GSS_SVC_PRIVACY:
 			/* placeholders for length and seq. number: */
 			svc_putnl(resv, 0);
 			svc_putnl(resv, 0);
-			break;
-		case RPC_GSS_SVC_PRIVACY:
 			if (unwrap_priv_data(rqstp, &rqstp->rq_arg,
 					gc->gc_seq, rsci->mechctx))
 				goto garbage_args;
-			/* placeholders for length and seq. number: */
-			svc_putnl(resv, 0);
-			svc_putnl(resv, 0);
 			break;
 		default:
 			goto auth_err;
@@ -1170,8 +1170,6 @@ svcauth_gss_accept(struct svc_rqst *rqstp, __be32 *authp)
 		goto out;
 	}
 garbage_args:
-	/* Restore write pointer to its original value: */
-	xdr_ressize_check(rqstp, reject_stat);
 	ret = SVC_GARBAGE;
 	goto out;
 auth_err:
-- 
1.5.5.rc1