From 6db8b56eed62baacaf37486e83378a72635c04cc Mon Sep 17 00:00:00 2001 From: Qanux Date: Wed, 11 Feb 2026 12:04:12 +0800 Subject: ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data() On the receive path, __ioam6_fill_trace_data() uses trace->nodelen to decide how much data to write for each node. It trusts this field as-is from the incoming packet, with no consistency check against trace->type (the 24-bit field that tells which data items are present). A crafted packet can set nodelen=0 while setting type bits 0-21, causing the function to write ~100 bytes past the allocated region (into skb_shared_info), which corrupts adjacent heap memory and leads to a kernel panic. Add a shared helper ioam6_trace_compute_nodelen() in ioam6.c to derive the expected nodelen from the type field, and use it: - in ioam6_iptunnel.c (send path, existing validation) to replace the open-coded computation; - in exthdrs.c (receive path, ipv6_hop_ioam) to drop packets whose nodelen is inconsistent with the type field, before any data is written. Per RFC 9197, bits 12-21 are each short (4-octet) fields, so they are included in IOAM6_MASK_SHORT_FIELDS (changed from 0xff100000 to 0xff1ffc00). Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace") Cc: stable@vger.kernel.org Signed-off-by: Junxi Qian Reviewed-by: Justin Iurman Link: https://patch.msgid.link/20260211040412.86195-1-qjx1298677004@gmail.com Signed-off-by: Jakub Kicinski --- include/net/ioam6.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/net/ioam6.h b/include/net/ioam6.h index 2cbbee6e806a..a75912fe247e 100644 --- a/include/net/ioam6.h +++ b/include/net/ioam6.h @@ -60,6 +60,8 @@ void ioam6_fill_trace_data(struct sk_buff *skb, struct ioam6_trace_hdr *trace, bool is_input); +u8 ioam6_trace_compute_nodelen(u32 trace_type); + int ioam6_init(void); void ioam6_exit(void); -- cgit v1.2.3