From: Xiang Mei The depth check in xfrm6_input_addr() is off by one: if (1 + sp->len == XFRM_MAX_DEPTH) goto drop; ... sp->xvec[sp->len++] = x; xfrm_input() can leave sp->len == XFRM_MAX_DEPTH, and the transport-mode receive path re-enters IPv6 input via xfrm_trans_reinject() with that secpath preserved. If the inner packet carries a destination-options HAO option or a type-2 routing header, xfrm6_input_addr() is called with sp->len == XFRM_MAX_DEPTH; the check (1 + 6 == 6) is false, so sp->xvec[sp->len++] writes one slot past the 6-element xvec[]. The write stays within the sec_path allocation (invisible to KASAN); UBSAN_BOUNDS flags it and panics under panic_on_warn. Use "sp->len >= XFRM_MAX_DEPTH", matching xfrm_input(). This also restores one chain level the old check rejected at sp->len == 5. UBSAN: array-index-out-of-bounds in net/ipv6/xfrm6_input.c:309:10 index 6 is out of range for type 'xfrm_state *[6]' Fixes: 9473e1f631de ("[XFRM] MIPv6: Fix to input RO state correctly.") Reported-by: Weiming Shi Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Xiang Mei Signed-off-by: Steffen Klassert --- net/ipv6/xfrm6_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv6/xfrm6_input.c b/net/ipv6/xfrm6_input.c index 89d0443b5307..07edef258984 100644 --- a/net/ipv6/xfrm6_input.c +++ b/net/ipv6/xfrm6_input.c @@ -247,7 +247,7 @@ int xfrm6_input_addr(struct sk_buff *skb, xfrm_address_t *daddr, goto drop; } - if (1 + sp->len == XFRM_MAX_DEPTH) { + if (sp->len >= XFRM_MAX_DEPTH) { XFRM_INC_STATS(net, LINUX_MIB_XFRMINBUFFERERROR); goto drop; } -- 2.43.0