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From 9213ad631513d0e67d9d31465c9cdb3f3dde0399 Mon Sep 17 00:00:00 2001
From: Waldemar Brodkorb <wbx@uclibc-ng.org>
Date: Fri, 5 Aug 2016 21:33:44 +0200
Subject: [PATCH 2/3] sunrpc: Do not use alloca in clntudp_call
CVE-2016-4429:
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).
From GNU libc:
https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commit;h=bc779a1a5b3035133024b21e2f339fe4219fb11c
Signed-off-by: Waldemar Brodkorb <wbx@uclibc-ng.org>
---
libc/inet/rpc/clnt_udp.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/libc/inet/rpc/clnt_udp.c b/libc/inet/rpc/clnt_udp.c
index 4fc55b7..ce7e9e6 100644
--- a/libc/inet/rpc/clnt_udp.c
+++ b/libc/inet/rpc/clnt_udp.c
@@ -368,9 +368,15 @@ 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;
@@ -395,10 +401,12 @@ 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
--
2.7.4 (Apple Git-66)
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