>From 39a008cc80e0373ed0cffdc2f27daba5592c2012 Mon Sep 17 00:00:00 2001
From: lena wang <lena.wang@xxxxxxxxxxxx>
Date: Tue, 20 Feb 2024 14:00:31 +0800
Subject: [PATCH] Add protection for bmp length out of range
UBSAN load reports an exception of BRK#5515 SHIFT_ISSUE:Bitwise shifts
that are out of bounds for their data type.
vmlinux get_bitmap(b=75) + 712
<net/netfilter/nf_conntrack_h323_asn1.c:0>
vmlinux decode_seq(bs=0xFFFFFFD008037000, f=0xFFFFFFD008037018,
level=134443100) + 1956
<net/netfilter/nf_conntrack_h323_asn1.c:592>
vmlinux decode_choice(base=0xFFFFFFD0080370F0, level=23843636) + 1216
<net/netfilter/nf_conntrack_h323_asn1.c:814>
vmlinux decode_seq(f=0xFFFFFFD0080371A8, level=134443500) + 812
<net/netfilter/nf_conntrack_h323_asn1.c:576>
vmlinux decode_choice(base=0xFFFFFFD008037280, level=0) + 1216
<net/netfilter/nf_conntrack_h323_asn1.c:814>
vmlinux DecodeRasMessage() + 304
<net/netfilter/nf_conntrack_h323_asn1.c:833>
vmlinux ras_help() + 684
<net/netfilter/nf_conntrack_h323_main.c:1728>
vmlinux nf_confirm() + 188
<net/netfilter/nf_conntrack_proto.c:137>
vmlinux ipv4_confirm() + 204
<net/netfilter/nf_conntrack_proto.c:169>
vmlinux nf_hook_entry_hookfn() + 56
<include/linux/netfilter.h:137>
vmlinux nf_hook_slow(s=0) + 156
<net/netfilter/core.c:584>
vmlinux nf_hook(pf=2, hook=1, sk=0, outdev=0) + 748
<include/linux/netfilter.h:254>
vmlinux NF_HOOK(pf=2, hook=1, sk=0, out=0) + 748
<include/linux/netfilter.h:297>
vmlinux ip_local_deliver() + 1072
<net/ipv4/ip_input.c:252>
vmlinux dst_input() + 64
<include/net/dst.h:443>
vmlinux ip_rcv_finish(sk=0) + 120
<net/ipv4/ip_input.c:435>
vmlinux NF_HOOK(pf=2, hook=0, sk=0, out=0) + 136
<include/linux/netfilter.h:299>
vmlinux ip_rcv() + 320
<net/ipv4/ip_input.c:546>
vmlinux deliver_skb(orig_dev=0xFFFFFFD0080B7F5C) + 268
<net/core/dev.c:2274>
vmlinux deliver_ptype_list_skb(orig_dev=0xFFFFFFD008037AB8) + 96
<net/core/dev.c:2289>
vmlinux __netif_receive_skb_core(pfmemalloc=false) + 4984
<net/core/dev.c:5328>
vmlinux __netif_receive_skb_one_core(pfmemalloc=false) + 72
<net/core/dev.c:5370>
vmlinux __netif_receive_skb() + 268
<net/core/dev.c:5486>
vmlinux process_backlog(quota=134446100) + 672
<net/core/dev.c:6393>
vmlinux napi_poll() + 312
<net/core/dev.c:6844>
vmlinux net_rx_action() + 732
<net/core/dev.c:6914>
vmlinux __do_softirq() + 712
<kernel/softirq.c:305>
vmlinux do_softirq_own_stack()
<include/linux/interrupt.h:578>
vmlinux invoke_softirq() + 152
<kernel/softirq.c:402>
vmlinux el0_svc() + 32
<arch/arm64/kernel/entry-common.c:357>
vmlinux el0_sync_handler() + 132
<arch/arm64/kernel/entry-common.c:373>
Due to abnormal data in skb->data, the extension bitmap length
exceeds 32 when decoding ras message then uses the length to make
a shift operation. It will change into negative after several loop.
UBSAN load could detect a negative shift as an undefined behaviour
and reports exception.
So we add the protection to avoid the length exceeding 32. Or else
it will return out of range error and stop decoding.
Signed-off-by: lena wang <lena.wang@xxxxxxxxxxxx>
---
net/netfilter/nf_conntrack_h323_asn1.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/netfilter/nf_conntrack_h323_asn1.c
b/net/netfilter/nf_conntrack_h323_asn1.c
index e697a824b001..85be1c589ef0 100644
--- a/net/netfilter/nf_conntrack_h323_asn1.c
+++ b/net/netfilter/nf_conntrack_h323_asn1.c
@@ -589,6 +589,8 @@ static int decode_seq(struct bitstr *bs, const
struct field_t *f,
bmp2_len = get_bits(bs, 7) + 1;
if (nf_h323_error_boundary(bs, 0, bmp2_len))
return H323_ERROR_BOUND;
+ if (bmp2_len > 32)
+ return H323_ERROR_RANGE;
bmp2 = get_bitmap(bs, bmp2_len);
bmp |= bmp2 >> f->sz;
if (base)
--
2.18.0
