From dac1ecc84cecb8e32a317d722ec24c3a3a28460b Mon Sep 17 00:00:00 2001 From: Shreeya Patel Date: Thu, 3 Jul 2025 19:52:48 +0000 Subject: [PATCH] sunrpc: handle SVC_GARBAGE during svc auth processing as auth error jira VULN-71607 cve CVE-2025-38089 commit-author Jeff Layton commit 94d10a4dba0bc482f2b01e39f06d5513d0f75742 upstream-diff A merge conflict was caused because the following commit doesn't exit in our tree: ab42f4d9a26f ("sunrpc: don't change ->sv_stats if it doesn't exist") tianshuo han reported a remotely-triggerable crash if the client sends a kernel RPC server a specially crafted packet. If decoding the RPC reply fails in such a way that SVC_GARBAGE is returned without setting the rq_accept_statp pointer, then that pointer can be dereferenced and a value stored there. If it's the first time the thread has processed an RPC, then that pointer will be set to NULL and the kernel will crash. In other cases, it could create a memory scribble. The server sunrpc code treats a SVC_GARBAGE return from svc_authenticate or pg_authenticate as if it should send a GARBAGE_ARGS reply. RFC 5531 says that if authentication fails that the RPC should be rejected instead with a status of AUTH_ERR. Handle a SVC_GARBAGE return as an AUTH_ERROR, with a reason of AUTH_BADCRED instead of returning GARBAGE_ARGS in that case. This sidesteps the whole problem of touching the rpc_accept_statp pointer in this situation and avoids the crash. Cc: stable@kernel.org Fixes: 29cd2927fb91 ("SUNRPC: Fix encoding of accepted but unsuccessful RPC replies") Reported-by: tianshuo han Reviewed-by: Chuck Lever Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever (cherry picked from commit 94d10a4dba0bc482f2b01e39f06d5513d0f75742) Signed-off-by: Shreeya Patel --- net/sunrpc/svc.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index e387d4d26990e..8c7ae3c595b29 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -1343,7 +1343,8 @@ svc_process_common(struct svc_rqst *rqstp) case SVC_OK: break; case SVC_GARBAGE: - goto err_garbage_args; + rqstp->rq_auth_stat = rpc_autherr_badcred; + goto err_bad_auth; case SVC_SYSERR: goto err_system_err; case SVC_DENIED: @@ -1478,13 +1479,6 @@ svc_process_common(struct svc_rqst *rqstp) *rqstp->rq_accept_statp = rpc_proc_unavail; goto sendit; -err_garbage_args: - svc_printk(rqstp, "failed to decode RPC header\n"); - - serv->sv_stats->rpcbadfmt++; - *rqstp->rq_accept_statp = rpc_garbage_args; - goto sendit; - err_system_err: serv->sv_stats->rpcbadfmt++; *rqstp->rq_accept_statp = rpc_system_err;