From 5e67ba9bb531e1ec6599a82a065dea9040b9ce50 Mon Sep 17 00:00:00 2001 From: Pengpeng Hou Date: Wed, 25 Mar 2026 15:41:52 +0800 Subject: [PATCH] net/ipv6: ioam6: prevent schema length wraparound in trace fill ioam6_fill_trace_data() stores the schema contribution to the trace length in a u8. With bit 22 enabled and the largest schema payload, sclen becomes 1 + 1020 / 4, wraps from 256 to 0, and bypasses the remaining-space check. __ioam6_fill_trace_data() then positions the write cursor without reserving the schema area but still copies the 4-byte schema header and the full schema payload, overrunning the trace buffer. Keep sclen in an unsigned int so the remaining-space check and the write cursor calculation both see the full schema length. Fixes: 8c6f6fa67726 ("ipv6: ioam: IOAM Generic Netlink API") Signed-off-by: Pengpeng Hou Reviewed-by: Justin Iurman Signed-off-by: David S. Miller --- net/ipv6/ioam6.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv6/ioam6.c b/net/ipv6/ioam6.c index b76f89d92e7b..3978773bec42 100644 --- a/net/ipv6/ioam6.c +++ b/net/ipv6/ioam6.c @@ -708,7 +708,7 @@ static void __ioam6_fill_trace_data(struct sk_buff *skb, struct ioam6_namespace *ns, struct ioam6_trace_hdr *trace, struct ioam6_schema *sc, - u8 sclen, bool is_input) + unsigned int sclen, bool is_input) { struct net_device *dev = skb_dst_dev(skb); struct timespec64 ts; @@ -939,7 +939,7 @@ void ioam6_fill_trace_data(struct sk_buff *skb, bool is_input) { struct ioam6_schema *sc; - u8 sclen = 0; + unsigned int sclen = 0; /* Skip if Overflow flag is set */