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

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

netfilter: nfconntrackh323: Add protection for bmp length out of range

UBSAN load reports an exception of BRK#5515 SHIFTISSUE:Bitwise shifts that are out of bounds for their data type.

vmlinux getbitmap(b=75) + 712

vmlinux decodeseq(bs=0xFFFFFFD008037000, f=0xFFFFFFD008037018, level=134443100) + 1956

vmlinux decodechoice(base=0xFFFFFFD0080370F0, level=23843636) + 1216

vmlinux decodeseq(f=0xFFFFFFD0080371A8, level=134443500) + 812

vmlinux decodechoice(base=0xFFFFFFD008037280, level=0) + 1216

vmlinux DecodeRasMessage() + 304

vmlinux rashelp() + 684

vmlinux nfconfirm() + 188

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.

— IBM

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

netfilter: nfconntrackh323: Add protection for bmp length out of range

UBSAN load reports an exception of BRK#5515 SHIFTISSUE:Bitwise shifts that are out of bounds for their data type.

vmlinux getbitmap(b=75) + 712 <net/netfilter/nfconntrackh323asn1.c:0> vmlinux decodeseq(bs=0xFFFFFFD008037000, f=0xFFFFFFD008037018, level=134443100) + 1956 <net/netfilter/nfconntrackh323asn1.c:592> vmlinux decodechoice(base=0xFFFFFFD0080370F0, level=23843636) + 1216 <net/netfilter/nfconntrackh323asn1.c:814> vmlinux decodeseq(f=0xFFFFFFD0080371A8, level=134443500) + 812 <net/netfilter/nfconntrackh323asn1.c:576> vmlinux decodechoice(base=0xFFFFFFD008037280, level=0) + 1216 <net/netfilter/nfconntrackh323asn1.c:814> vmlinux DecodeRasMessage() + 304 <net/netfilter/nfconntrackh323asn1.c:833> vmlinux rashelp() + 684 <net/netfilter/nfconntrackh323main.c:1728> vmlinux nfconfirm() + 188 <net/netfilter/nfconntrackproto.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.

— NVD