diff options
| author | Xiang Mei <xmei5@asu.edu> | 2026-07-12 16:42:01 -0700 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2026-07-22 19:47:17 +0200 |
| commit | db3d0e0e5d4bc5ab4fe445b9f413d1b486508ca5 (patch) | |
| tree | 49ea61c90ff40234bee83d2d34e0267defe5ecb2 | |
| parent | fca68249b6f5e84859b200b54cb5e0aef98f2b3a (diff) | |
netfilter: nf_conntrack_sip: widen NAT rewrite delta to s32 in sip_help_tcp()
sip_help_tcp() stores the size change of each NAT-rewritten SIP message
in s16 diff and accumulates it in s16 tdiff, but a single message can
grow by more than S16_MAX while the packet stays under the 65535
enlarge_skb() limit: nf_nat_sip() rewrites every matching URI, and a long
Contact list expands the message by tens of kilobytes. diff then wraps,
and "datalen = datalen + diff - msglen" yields a huge unsigned datalen,
so the next iteration's ct_sip_get_header() reads past the linearized skb
tail.
Widen diff, tdiff and the seq_adjust hook to s32. Both are bounded by the
65535 byte packet limit, and the seqadj core is already s32
(nf_ct_seqadj_set() takes s32), so no previously accepted input is
rejected.
BUG: KASAN: use-after-free in ct_sip_get_header (net/netfilter/nf_conntrack_sip.c:464)
Read of size 1 at addr ffff888010800000 by task ksoftirqd/1/25
ct_sip_get_header (net/netfilter/nf_conntrack_sip.c:464)
sip_help_tcp (net/netfilter/nf_conntrack_sip.c:1694)
nf_confirm (net/netfilter/nf_conntrack_proto.c:183)
nf_hook_slow (net/netfilter/core.c:619)
ip6_output (net/ipv6/ip6_output.c:246)
ip6_forward (net/ipv6/ip6_output.c:690)
ipv6_rcv (net/ipv6/ip6_input.c:351)
__netif_receive_skb_one_core (net/core/dev.c:6212)
process_backlog (net/core/dev.c:6676)
__napi_poll (net/core/dev.c:7735)
net_rx_action (net/core/dev.c:7955)
handle_softirqs (kernel/softirq.c:622)
run_ksoftirqd (kernel/softirq.c:1076)
...
Fixes: f5b321bd37fb ("netfilter: nf_conntrack_sip: add TCP support")
Reported-by: Weiming Shi <bestswngs@gmail.com>
Link: https://patch.msgid.link/netfilter-devel/20260712234201.3213635-1-xmei5@asu.edu
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Xiang Mei <xmei5@asu.edu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
| -rw-r--r-- | include/linux/netfilter/nf_conntrack_sip.h | 2 | ||||
| -rw-r--r-- | net/netfilter/nf_conntrack_sip.c | 2 | ||||
| -rw-r--r-- | net/netfilter/nf_nat_sip.c | 2 |
3 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/netfilter/nf_conntrack_sip.h b/include/linux/netfilter/nf_conntrack_sip.h index dbc614dfe0d5..aafa0c04f917 100644 --- a/include/linux/netfilter/nf_conntrack_sip.h +++ b/include/linux/netfilter/nf_conntrack_sip.h @@ -115,7 +115,7 @@ struct nf_nat_sip_hooks { unsigned int *datalen); void (*seq_adjust)(struct sk_buff *skb, - unsigned int protoff, s16 off); + unsigned int protoff, s32 off); unsigned int (*expect)(struct sk_buff *skb, unsigned int protoff, diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c index f3f90a866338..e4a70d1d77b0 100644 --- a/net/netfilter/nf_conntrack_sip.c +++ b/net/netfilter/nf_conntrack_sip.c @@ -1663,7 +1663,7 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff, unsigned int matchoff, matchlen; unsigned int msglen, origlen; const char *dptr, *end; - s16 diff, tdiff = 0; + s32 diff, tdiff = 0; int ret = NF_ACCEPT; unsigned long clen; bool term; diff --git a/net/netfilter/nf_nat_sip.c b/net/netfilter/nf_nat_sip.c index aea02f6aff09..a93eaf0f7d30 100644 --- a/net/netfilter/nf_nat_sip.c +++ b/net/netfilter/nf_nat_sip.c @@ -321,7 +321,7 @@ next: } static void nf_nat_sip_seq_adjust(struct sk_buff *skb, unsigned int protoff, - s16 off) + s32 off) { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |