From bdce95930e1d9a7d013d1ba78740243491262879 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Mon, 23 May 2016 20:18:34 +0200 Subject: [PATCH] CVE-2016-4429: sunrpc: Do not use alloca in clntudp_call [BZ #20112] The call is technically in a loop, and under certain circumstances (which are quite difficult to reproduce in a test case), alloca can be invoked repeatedly during a single call to clntudp_call. As a result, the available stack space can be exhausted (even though individual alloca sizes are bounded implicitly by what can fit into a UDP packet, as a side effect of the earlier successful send operation). (cherry picked from commit bc779a1a5b3035133024b21e2f339fe4219fb11c) --- ChangeLog | 7 +++++++ NEWS | 4 ++++ sunrpc/clnt_udp.c | 10 +++++++++- 3 files changed, 20 insertions(+), 1 deletion(-) diff --git a/sunrpc/clnt_udp.c b/sunrpc/clnt_udp.c index a6cf5f1..4d9acb1 100644 --- a/sunrpc/clnt_udp.c +++ b/sunrpc/clnt_udp.c @@ -388,9 +388,15 @@ send_again: struct sock_extended_err *e; struct sockaddr_in err_addr; struct iovec iov; - char *cbuf = (char *) alloca (outlen + 256); + char *cbuf = malloc (outlen + 256); int ret; + if (cbuf == NULL) + { + cu->cu_error.re_errno = errno; + return (cu->cu_error.re_status = RPC_CANTRECV); + } + iov.iov_base = cbuf + 256; iov.iov_len = outlen; msg.msg_name = (void *) &err_addr; @@ -415,10 +421,12 @@ send_again: cmsg = CMSG_NXTHDR (&msg, cmsg)) if (cmsg->cmsg_level == SOL_IP && cmsg->cmsg_type == IP_RECVERR) { + free (cbuf); e = (struct sock_extended_err *) CMSG_DATA(cmsg); cu->cu_error.re_errno = e->ee_errno; return (cu->cu_error.re_status = RPC_CANTRECV); } + free (cbuf); } #endif do -- 2.9.3