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netfilter: nf_conntrack_h323: Add protection for bmp length out of range

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[ Upstream commit 767146637efc528b5e3d31297df115e85a2fd362 ]

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.

Fixes: 5e35941d9901 ("[NETFILTER]: Add H.323 conntrack/NAT helper")
Signed-off-by: Lena Wang <lena.wang@mediatek.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 98db42191329c679f4ca52bec0b319689e1ad8cb)
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
This commit is contained in:
Lena Wang 2024-03-05 11:38:55 +00:00 committed by Vegard Nossum
parent 74a4c76141
commit 1c31b4059c
1 changed files with 4 additions and 0 deletions
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4
net/netfilter/nf_conntrack_h323_asn1.c
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@ -545,6 +545,8 @@ static int decode_seq(struct bitstr *bs, const struct field_t *f,
/* Get fields bitmap */
if (nf_h323_error_boundary(bs, 0, f->sz))
return H323_ERROR_BOUND;
if (f->sz > 32)
return H323_ERROR_RANGE;
bmp = get_bitmap(bs, f->sz);
if (base)
*(unsigned int *)base = bmp;
@ -601,6 +603,8 @@ 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)