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net/packet: fix overflow in tpacket_rcv (CVE-2020-14386)

remotes/origin/buster
Salvatore Bonaccorso 1 year ago
parent
commit
ad72e888ee
  1. 1
      debian/changelog
  2. 57
      debian/patches/bugfix/all/net-packet-fix-overflow-in-tpacket_rcv.patch
  3. 1
      debian/patches/series

1
debian/changelog

@ -732,6 +732,7 @@ linux (4.19.143-1) UNRELEASED; urgency=medium
* ACPI: configfs: Disallow loading ACPI tables when locked down
(CVE-2020-15780)
* [rt] Update to 4.19.142-rt63
* net/packet: fix overflow in tpacket_rcv (CVE-2020-14386)
-- Salvatore Bonaccorso <carnil@debian.org> Tue, 04 Aug 2020 16:33:40 +0200

57
debian/patches/bugfix/all/net-packet-fix-overflow-in-tpacket_rcv.patch

@ -0,0 +1,57 @@
From: Or Cohen <orcohen@paloaltonetworks.com>
Date: Thu, 3 Sep 2020 21:05:28 -0700
Subject: net/packet: fix overflow in tpacket_rcv
Origin: https://git.kernel.org/linus/acf69c946233259ab4d64f8869d4037a198c7f06
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2020-14386
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.
This addresses CVE-2020-14386
Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt")
Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[Salvatore Bonaccorso: Backport to v4.19.y:
- Adjust for context changes
- Revert change to use atomic_inc as v4.19.y does not contain 8e8e2951e309
("net/packet: make tp_drops atomic") introduced in v5.3-rc1
]
---
net/packet/af_packet.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2162,7 +2162,8 @@ static int tpacket_rcv(struct sk_buff *s
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 timespec ts;
__u32 ts_status;
@@ -2225,6 +2226,12 @@ static int tpacket_rcv(struct sk_buff *s
}
macoff = netoff - maclen;
}
+ if (netoff > USHRT_MAX) {
+ spin_lock(&sk->sk_receive_queue.lock);
+ po->stats.stats1.tp_drops++;
+ spin_unlock(&sk->sk_receive_queue.lock);
+ goto drop_n_restore;
+ }
if (po->tp_version <= TPACKET_V2) {
if (macoff + snaplen > po->rx_ring.frame_size) {
if (po->copy_thresh &&

1
debian/patches/series

@ -297,5 +297,6 @@ features/arm/staging-vc04_services-Use-correct-cache-line-size.patch
# Security fixes
debian/i386-686-pae-pci-set-pci-nobios-by-default.patch
debian/ntfs-mark-it-as-broken.patch
bugfix/all/net-packet-fix-overflow-in-tpacket_rcv.patch
# ABI maintenance

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