[PATCH 5.10 007/126] rpc: fix NULL dereference on kmalloc failure

Greg Kroah-Hartman
2021-04-05T09:10:46Z

From: J. Bruce Fields <bfields@redhat.com>

[ Upstream commit 0ddc942394013f08992fc379ca04cffacbbe3dae ]

I think this is unlikely but possible:

svc_authenticate sets rq_authop and calls svcauth_gss_accept. The
kmalloc(sizeof(*svcdata), GFP_KERNEL) fails, leaving rq_auth_data NULL,
and returning SVC_DENIED.

This causes svc_process_common to go to err_bad_auth, and eventually
call svc_authorise. That calls ->release == svcauth_gss_release, which
tries to dereference rq_auth_data.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Link: https://lore.kernel.org/linux-nfs/3F1B347F-B809-478F-A1E9-0BE98E22B0F0@oracle.com/T/#t
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sunrpc/auth_gss/svcauth_gss.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index bd4678db9d76..6dff64374bfe 100644
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -1825,11 +1825,14 @@ static int
svcauth_gss_release(struct svc_rqst *rqstp)
{
struct gss_svc_data *gsd = (struct gss_svc_data *)rqstp->rq_auth_data;
- struct rpc_gss_wire_cred *gc = &gsd->clcred;
+ struct rpc_gss_wire_cred *gc;
struct xdr_buf *resbuf = &rqstp->rq_res;
int stat = -EINVAL;
struct sunrpc_net *sn = net_generic(SVC_NET(rqstp), sunrpc_net_id);

+ if (!gsd)
+ goto out;
+ gc = &gsd->clcred;
if (gc->gc_proc != RPC_GSS_PROC_DATA)
goto out;
/* Release can be called twice, but we only wrap once. */
@@ -1870,10 +1873,10 @@ out_err:
if (rqstp->rq_cred.cr_group_info)
put_group_info(rqstp->rq_cred.cr_group_info);
rqstp->rq_cred.cr_group_info = NULL;
- if (gsd->rsci)
+ if (gsd && gsd->rsci) {
cache_put(&gsd->rsci->h, sn->rsc_cache);
- gsd->rsci = NULL;
-
+ gsd->rsci = NULL;
+ }
return stat;
}

--
2.30.1