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sys-kernel: Include patch for overflow in tpacket_rcv

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A memory corruption vulnerability in AF_PACKET causes the kernel to
panic or enter undefined behavior, tracked as CVE-2020-14386.
While the proposed patch is not included in an upstream release,
include it as downstream patch.
Further information and PoC:
https://www.openwall.com/lists/oss-security/2020/09/03/3
This commit is contained in:
Kai Lüke 2020-09-04 17:48:55 +02:00
parent 21bfbeb2e9
commit dd0138a9c8
2 changed files with 51 additions and 0 deletions
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1
sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-sources/coreos-sources-5.4.62.ebuild vendored
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@ -36,4 +36,5 @@ UNIPATCH_LIST="
${PATCH_DIR}/z0002-tools-objtool-Makefile-Don-t-fail-on-fallthrough-wit.patch \ ${PATCH_DIR}/z0002-tools-objtool-Makefile-Don-t-fail-on-fallthrough-wit.patch \
${PATCH_DIR}/z0003-net-netfilter-add-nf_conntrack_ipv4-compat-module-fo.patch \ ${PATCH_DIR}/z0003-net-netfilter-add-nf_conntrack_ipv4-compat-module-fo.patch \
${PATCH_DIR}/z0004-add-wireguard-module.patch \ ${PATCH_DIR}/z0004-add-wireguard-module.patch \
${PATCH_DIR}/z0005-net_packet_fix_overflow_in_tpacket_rcv_patch.patch \
" "

50
sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-sources/files/5.4/z0005-net_packet_fix_overflow_in_tpacket_rcv_patch.patch vendored Normal file
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@ -0,0 +1,50 @@
From 3ad04c9555b93ac6a374b0921ad41849caf22067 Mon Sep 17 00:00:00 2001
From: Or Cohen <orcohen@paloaltonetworks.com>
Date: Sun, 30 Aug 2020 20:04:51 +0300
Subject: [PATCH] net/packet: fix overflow in tpacket_rcv
Using tp_reserve to calculate netoff can overflow as
tp_reserve is unsigned int and netoff is unsigned short.
This may lead to macoff receving a smaller value then
sizeof(struct virtio_net_hdr), and if po->has_vnet_hdr
is set, an out-of-bounds write will occur when
calling virtio_net_hdr_from_skb.
The bug is fixed by converting netoff to unsigned int
and checking if it exceeds USHRT_MAX.
Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt")
Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com>
---
net/packet/af_packet.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 29bd405adbbd..d37435906859 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2168,7 +2168,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
int skb_len = skb->len;
unsigned int snaplen, res;
unsigned long status = TP_STATUS_USER;
- unsigned short macoff, netoff, hdrlen;
+ unsigned short macoff, hdrlen;
+ unsigned int netoff;
struct sk_buff *copy_skb = NULL;
struct timespec64 ts;
__u32 ts_status;
@@ -2237,6 +2238,10 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
}
macoff = netoff - maclen;
}
+ if (netoff > USHRT_MAX) {
+ atomic_inc(&po->tp_drops);
+ goto drop_n_restore;
+ }
if (po->tp_version <= TPACKET_V2) {
if (macoff + snaplen > po->rx_ring.frame_size) {
if (po->copy_thresh &&
--
2.17.1