From 767146637efc528b5e3d31297df115e85a2fd362 Mon Sep 17 00:00:00 2001 From: Lena Wang Date: Tue, 5 Mar 2024 11:38:55 +0000 Subject: [PATCH] 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 vmlinux decode_seq(bs=0xFFFFFFD008037000, f=0xFFFFFFD008037018, level=134443100) + 1956 vmlinux decode_choice(base=0xFFFFFFD0080370F0, level=23843636) + 1216 vmlinux decode_seq(f=0xFFFFFFD0080371A8, level=134443500) + 812 vmlinux decode_choice(base=0xFFFFFFD008037280, level=0) + 1216 vmlinux DecodeRasMessage() + 304 vmlinux ras_help() + 684 vmlinux nf_confirm() + 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. Fixes: 5e35941d9901 ("[NETFILTER]: Add H.323 conntrack/NAT helper") Signed-off-by: Lena Wang Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_h323_asn1.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/netfilter/nf_conntrack_h323_asn1.c b/net/netfilter/nf_conntrack_h323_asn1.c index e697a824b001..540d97715bd2 100644 --- a/net/netfilter/nf_conntrack_h323_asn1.c +++ b/net/netfilter/nf_conntrack_h323_asn1.c @@ -533,6 +533,8 @@ 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; @@ -589,6 +591,8 @@ 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)