64 lines
2.7 KiB
Diff
64 lines
2.7 KiB
Diff
From c38d41134085193efd5b237cf513ad5b3421a60d Mon Sep 17 00:00:00 2001
|
|
From: Xiang Mei <xmei5@asu.edu>
|
|
Date: Tue, 9 Jun 2026 15:55:02 -0700
|
|
Subject: [PATCH] netfilter: nf_log: validate MAC header was set before dumping
|
|
it
|
|
|
|
[ Upstream commit a84b6fedbc97078788be78dbdd7517d143ad1a77 ]
|
|
|
|
The fallback path of dump_mac_header() guards the MAC header access
|
|
only with "skb->mac_header != skb->network_header", without checking
|
|
skb_mac_header_was_set(). When the MAC header is unset, mac_header is
|
|
0xffff, so the test passes and skb_mac_header(skb) returns
|
|
skb->head + 0xffff, ~64 KiB past the buffer; the loop then reads
|
|
dev->hard_header_len bytes out of bounds into the kernel log.
|
|
|
|
This is reachable via the netdev logger: nf_log_unknown_packet() calls
|
|
dump_mac_header() unconditionally, and an skb sent through AF_PACKET
|
|
with PACKET_QDISC_BYPASS reaches the egress hook with mac_header still
|
|
unset (__dev_queue_xmit(), which would reset it, is bypassed).
|
|
|
|
Add the skb_mac_header_was_set() check the ARPHRD_ETHER path already
|
|
uses, and replace the open-coded MAC header length test with
|
|
skb_mac_header_len(). Only skbs with an unset MAC header are affected;
|
|
valid ones are dumped as before.
|
|
|
|
BUG: KASAN: slab-out-of-bounds in dump_mac_header (net/netfilter/nf_log_syslog.c:831)
|
|
Read of size 1 at addr ffff88800ea49d3f by task exploit/148
|
|
Call Trace:
|
|
kasan_report (mm/kasan/report.c:595)
|
|
dump_mac_header (net/netfilter/nf_log_syslog.c:831)
|
|
nf_log_netdev_packet (net/netfilter/nf_log_syslog.c:938 net/netfilter/nf_log_syslog.c:963)
|
|
nf_log_packet (net/netfilter/nf_log.c:260)
|
|
nft_log_eval (net/netfilter/nft_log.c:60)
|
|
nft_do_chain (net/netfilter/nf_tables_core.c:285)
|
|
nft_do_chain_netdev (net/netfilter/nft_chain_filter.c:307)
|
|
nf_hook_slow (net/netfilter/core.c:619)
|
|
nf_hook_direct_egress (net/packet/af_packet.c:257)
|
|
packet_xmit (net/packet/af_packet.c:280)
|
|
packet_sendmsg (net/packet/af_packet.c:3114)
|
|
__sys_sendto (net/socket.c:2265)
|
|
|
|
Fixes: 7eb9282cd0ef ("netfilter: ipt_LOG/ip6t_LOG: add option to print decoded MAC header")
|
|
Reported-by: Weiming Shi <bestswngs@gmail.com>
|
|
Assisted-by: Claude:claude-opus-4-8
|
|
Signed-off-by: Xiang Mei <xmei5@asu.edu>
|
|
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
|
|
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
|
|
diff --git a/net/netfilter/nf_log_syslog.c b/net/netfilter/nf_log_syslog.c
|
|
index 5840222..09b9152 100644
|
|
--- a/net/netfilter/nf_log_syslog.c
|
|
+++ b/net/netfilter/nf_log_syslog.c
|
|
@@ -799,8 +799,8 @@ static void dump_mac_header(struct nf_log_buf *m,
|
|
|
|
fallback:
|
|
nf_log_buf_add(m, "MAC=");
|
|
- if (dev->hard_header_len &&
|
|
- skb->mac_header != skb->network_header) {
|
|
+ if (dev->hard_header_len && skb_mac_header_was_set(skb) &&
|
|
+ skb_mac_header_len(skb) != 0) {
|
|
const unsigned char *p = skb_mac_header(skb);
|
|
unsigned int i;
|
|
|