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backport fixes for missing verification for short frames in network tap/tun devices

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A malicious guest with virtio-net device could apparently crash the
host [0]. Fixes CVE-2024-41090 and CVE-2024-41091. Reported in the
community forum [1].

[0]: https://seclists.org/oss-sec/2024/q3/110
[1]: https://forum.proxmox.com/threads/151813/

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
This commit is contained in:
Fiona Ebner 2024-07-26 13:10:44 +02:00 committed by Fabian Grünbichler
parent 69b55c504c
commit a791b86e0a
2 changed files with 103 additions and 0 deletions
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52
patches/kernel/0021-tap-add-missing-verification-for-short-frame.patch Normal file
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@ -0,0 +1,52 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Si-Wei Liu <si-wei.liu@oracle.com>
Date: Wed, 24 Jul 2024 10:04:51 -0700
Subject: [PATCH] tap: add missing verification for short frame
The cited commit missed to check against the validity of the frame length
in the tap_get_user_xdp() path, which could cause a corrupted skb to be
sent downstack. Even before the skb is transmitted, the
tap_get_user_xdp()-->skb_set_network_header() may assume the size is more
than ETH_HLEN. Once transmitted, this could either cause out-of-bound
access beyond the actual length, or confuse the underlayer with incorrect
or inconsistent header length in the skb metadata.
In the alternative path, tap_get_user() already prohibits short frame which
has the length less than Ethernet header size from being transmitted.
This is to drop any frame shorter than the Ethernet header size just like
how tap_get_user() does.
CVE: CVE-2024-41090
Link: https://lore.kernel.org/netdev/1717026141-25716-1-git-send-email-si-wei.liu@oracle.com/
Fixes: 0efac27791ee ("tap: accept an array of XDP buffs through sendmsg()")
Cc: stable@vger.kernel.org
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Link: https://patch.msgid.link/20240724170452.16837-2-dongli.zhang@oracle.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit ed7f2afdd0e043a397677e597ced0830b83ba0b3)
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
drivers/net/tap.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 9f0495e8df4d..feeeac715c18 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -1177,6 +1177,11 @@ static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp)
struct sk_buff *skb;
int err, depth;
+ if (unlikely(xdp->data_end - xdp->data < ETH_HLEN)) {
+ err = -EINVAL;
+ goto err;
+ }
+
if (q->flags & IFF_VNET_HDR)
vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);

51
patches/kernel/0022-tun-add-missing-verification-for-short-frame.patch Normal file
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@ -0,0 +1,51 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Dongli Zhang <dongli.zhang@oracle.com>
Date: Wed, 24 Jul 2024 10:04:52 -0700
Subject: [PATCH] tun: add missing verification for short frame
The cited commit missed to check against the validity of the frame length
in the tun_xdp_one() path, which could cause a corrupted skb to be sent
downstack. Even before the skb is transmitted, the
tun_xdp_one-->eth_type_trans() may access the Ethernet header although it
can be less than ETH_HLEN. Once transmitted, this could either cause
out-of-bound access beyond the actual length, or confuse the underlayer
with incorrect or inconsistent header length in the skb metadata.
In the alternative path, tun_get_user() already prohibits short frame which
has the length less than Ethernet header size from being transmitted for
IFF_TAP.
This is to drop any frame shorter than the Ethernet header size just like
how tun_get_user() does.
CVE: CVE-2024-41091
Inspired-by: https://lore.kernel.org/netdev/1717026141-25716-1-git-send-email-si-wei.liu@oracle.com/
Fixes: 043d222f93ab ("tuntap: accept an array of XDP buffs through sendmsg()")
Cc: stable@vger.kernel.org
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Si-Wei Liu <si-wei.liu@oracle.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Link: https://patch.msgid.link/20240724170452.16837-3-dongli.zhang@oracle.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 049584807f1d797fc3078b68035450a9769eb5c3)
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
drivers/net/tun.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 86515f0c2b6c..e9cd3b810e2c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2459,6 +2459,9 @@ static int tun_xdp_one(struct tun_struct *tun,
bool skb_xdp = false;
struct page *page;
+ if (unlikely(datasize < ETH_HLEN))
+ return -EINVAL;
+
xdp_prog = rcu_dereference(tun->xdp_prog);
if (xdp_prog) {
if (gso->gso_type) {