This is a note to let you know that I've just added the patch titled
netfilter: nf_conntrack_h323: Add protection for bmp length out of range
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-nf_conntrack_h323-add-protection-for-bmp-l.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 65c0b33d6b1b3122636d0365525a982ccfd2d9d0
Author: Lena Wang <lena.wang@xxxxxxxxxxxx>
Date: Tue Mar 5 11:38:55 2024 +0000
netfilter: nf_conntrack_h323: Add protection for bmp length out of range
[ 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@xxxxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/netfilter/nf_conntrack_h323_asn1.c b/net/netfilter/nf_conntrack_h323_asn1.c
index 4c2ef42e189cb..82dae553a5fc7 100644
--- a/net/netfilter/nf_conntrack_h323_asn1.c
+++ b/net/netfilter/nf_conntrack_h323_asn1.c
@@ -536,6 +536,8 @@ 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;
@@ -592,6 +594,8 @@ 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)
