linux-kernel - [PATCH] tools/hv: Check the source of netlink messages to be the kernel

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Date:	Thu,  7 Jun 2012 11:07:48 +0200
From:	Marcus Meissner <meissner@...e.de>
To:	gregkh@...uxfoundation.org, kys@...rosoft.com,
	dan.carpenter@...cle.com, haiyangz@...rosoft.com, jkosina@...e.cz,
	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	Marcus Meissner <meissner@...e.de>,
	Sebastian Krahmer <krahmer@...e.de>,
	Olaf Hering <ohering@...e.de>
Subject: [PATCH] tools/hv: Check the source of netlink messages to be the kernel

Hi,

The hyper-v userspace helper daemon receives and handles netlink
messages. It assumes them to be from the kernel, but does not check
that.

This patch adds this checking (nl_pid == 0).

CVE-2012-2669

Ciao, Marcus

Signed-off-by: Marcus Meissner <meissner@...e.de>
Signed-off-by: Sebastian Krahmer <krahmer@...e.de>
Signed-off-by: Olaf Hering <ohering@...e.de>
---
 tools/hv/hv_kvp_daemon.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/hv/hv_kvp_daemon.c b/tools/hv/hv_kvp_daemon.c
index 146fd61..f0566c8 100644
--- a/tools/hv/hv_kvp_daemon.c
+++ b/tools/hv/hv_kvp_daemon.c
@@ -701,14 +701,16 @@ int main(void)
 	pfd.fd = fd;
 
 	while (1) {
+		struct sockaddr *addr_p = (struct sockaddr *) &addr;
+		socklen_t addr_l = sizeof(addr);
 		pfd.events = POLLIN;
 		pfd.revents = 0;
 		poll(&pfd, 1, -1);
 
-		len = recv(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0);
+		len = recvfrom(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0, addr_p, &addr_l);
 
-		if (len < 0) {
-			syslog(LOG_ERR, "recv failed; error:%d", len);
+		if (len < 0 || addr.nl_pid) {
+			syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s", addr.nl_pid, errno, strerror(errno));
 			close(fd);
 			return -1;
 		}
-- 
1.7.9.2

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