Subject: CVE-2024-26851: netfilter: nf_conntrack_h323: Add protection for bmp length out of range

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_conntrack_h323: 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>

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.

The Linux kernel CVE team has assigned CVE-2024-26851 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 2.6.17 with commit 5e35941d9901 and fixed in 4.19.310 with commit 98db42191329
	Issue introduced in 2.6.17 with commit 5e35941d9901 and fixed in 5.4.272 with commit 4bafcc43baf7
	Issue introduced in 2.6.17 with commit 5e35941d9901 and fixed in 5.10.213 with commit ccd1108b16ab
	Issue introduced in 2.6.17 with commit 5e35941d9901 and fixed in 5.15.152 with commit b3c0f5538205
	Issue introduced in 2.6.17 with commit 5e35941d9901 and fixed in 6.1.82 with commit 39001e3c4200
	Issue introduced in 2.6.17 with commit 5e35941d9901 and fixed in 6.6.22 with commit 014a807f1cc9
	Issue introduced in 2.6.17 with commit 5e35941d9901 and fixed in 6.7.10 with commit 80ee5054435a
	Issue introduced in 2.6.17 with commit 5e35941d9901 and fixed in 6.8 with commit 767146637efc

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-26851
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	net/netfilter/nf_conntrack_h323_asn1.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/98db42191329c679f4ca52bec0b319689e1ad8cb
	https://git.kernel.org/stable/c/4bafcc43baf7bcf93566394dbd15726b5b456b7a
	https://git.kernel.org/stable/c/ccd1108b16ab572d9bf635586b0925635dbd6bbc
	https://git.kernel.org/stable/c/b3c0f553820516ad4b62a9390ecd28d6f73a7b13
	https://git.kernel.org/stable/c/39001e3c42000e7c2038717af0d33c32319ad591
	https://git.kernel.org/stable/c/014a807f1cc9c9d5173c1cd935835553b00d211c
	https://git.kernel.org/stable/c/80ee5054435a11c87c9a4f30f1ff750080c96416
	https://git.kernel.org/stable/c/767146637efc528b5e3d31297df115e85a2fd362