Patchwork [2/3,RESEND] net: packet: fix information leak to userland

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Submitter Kulikov Vasiliy
Date Nov. 10, 2010, 6:29 p.m.
Message ID <1289413760-12510-1-git-send-email-segooon@gmail.com>
Download mbox | patch
Permalink /patch/70675/
State Accepted
Delegated to: David Miller
Headers show

Comments

Kulikov Vasiliy - Nov. 10, 2010, 6:29 p.m.
packet_getname_spkt() doesn't initialize all members of sa_data field of
sockaddr struct if strlen(dev->name) < 13.  This structure is then copied
to userland.  It leads to leaking of contents of kernel stack memory.
We have to fully fill sa_data with strncpy() instead of strlcpy().

The same with packet_getname(): it doesn't initialize sll_pkttype field of
sockaddr_ll.  Set it to zero.

Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
---
 Compile tested.

 net/packet/af_packet.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
David Miller - Nov. 10, 2010, 8:09 p.m.
From: Vasiliy Kulikov <segooon@gmail.com>
Date: Wed, 10 Nov 2010 21:29:18 +0300

> packet_getname_spkt() doesn't initialize all members of sa_data field of
> sockaddr struct if strlen(dev->name) < 13.  This structure is then copied
> to userland.  It leads to leaking of contents of kernel stack memory.
> We have to fully fill sa_data with strncpy() instead of strlcpy().
> 
> The same with packet_getname(): it doesn't initialize sll_pkttype field of
> sockaddr_ll.  Set it to zero.
> 
> Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>

Applied.
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Patch

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 3616f27..0856a13 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1719,7 +1719,7 @@  static int packet_getname_spkt(struct socket *sock, struct sockaddr *uaddr,
 	rcu_read_lock();
 	dev = dev_get_by_index_rcu(sock_net(sk), pkt_sk(sk)->ifindex);
 	if (dev)
-		strlcpy(uaddr->sa_data, dev->name, 15);
+		strncpy(uaddr->sa_data, dev->name, 14);
 	else
 		memset(uaddr->sa_data, 0, 14);
 	rcu_read_unlock();
@@ -1742,6 +1742,7 @@  static int packet_getname(struct socket *sock, struct sockaddr *uaddr,
 	sll->sll_family = AF_PACKET;
 	sll->sll_ifindex = po->ifindex;
 	sll->sll_protocol = po->num;
+	sll->sll_pkttype = 0;
 	rcu_read_lock();
 	dev = dev_get_by_index_rcu(sock_net(sk), po->ifindex);
 	if (dev) {