Bug 1223074 (CVE-2024-26851)

Summary: VUL-0: CVE-2024-26851: kernel: netfilter: nf_conntrack_h323: bmp length out of range
Product: [Novell Products] SUSE Security Incidents Reporter: SMASH SMASH <smash_bz>
Component: IncidentsAssignee: Karasulli <vasant.karasulli>
Status: NEW --- QA Contact: Security Team bot <security-team>
Severity: Normal    
Priority: P3 - Medium CC: mkoutny, thomas.leroy, vasant.karasulli
Version: unspecified   
Target Milestone: ---   
Hardware: Other   
OS: Other   
URL: https://smash.suse.de/issue/402356/
Whiteboard: CVSSv3.1:SUSE:CVE-2024-26851:5.5:(AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Found By: Security Response Team Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description SMASH SMASH 2024-04-18 11:25:22 UTC 
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.

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2024-26851
https://www.cve.org/CVERecord?id=CVE-2024-26851
https://git.kernel.org/stable/c/014a807f1cc9c9d5173c1cd935835553b00d211c
https://git.kernel.org/stable/c/39001e3c42000e7c2038717af0d33c32319ad591
https://git.kernel.org/stable/c/4bafcc43baf7bcf93566394dbd15726b5b456b7a
https://git.kernel.org/stable/c/767146637efc528b5e3d31297df115e85a2fd362
https://git.kernel.org/stable/c/80ee5054435a11c87c9a4f30f1ff750080c96416
https://git.kernel.org/stable/c/98db42191329c679f4ca52bec0b319689e1ad8cb
https://git.kernel.org/stable/c/b3c0f553820516ad4b62a9390ecd28d6f73a7b13
https://git.kernel.org/stable/c/ccd1108b16ab572d9bf635586b0925635dbd6bbc
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2024/CVE-2024-26851.mbox
https://bugzilla.redhat.com/show_bug.cgi?id=2275750