ila_csum_adjust_transport() caches ip6h = ipv6_hdr(skb) before calling pskb_may_pull(). On a non-linear skb whose transport header sits in a page fragment, pskb_may_pull() can call __pskb_pull_tail() / pskb_expand_head() and free the old skb head, leaving ip6h dangling; the following get_csum_diff(ip6h, p) then reads freed memory. ila_update_ipv6_locator() has the same pattern and additionally writes the new locator through the stale destination-address pointer. Impact: a remote IPv6 packet routed through a configured ILA csum-adjust-transport route or receive-side mapping triggers a slab-use-after-free in ila_update_ipv6_locator() (KASAN). The route or mapping requires CAP_NET_ADMIN to configure, but trigger packets are unauthenticated once it exists. Reload ip6h (and the derived iaddr) after each pskb_may_pull() before use, matching the transport-header reload the code already performs. Fixes: 33f11d16142b ("ila: Create net/ipv6/ila directory") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Michael Bommarito --- net/ipv6/ila/ila_common.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/ipv6/ila/ila_common.c b/net/ipv6/ila/ila_common.c index e71571455c8a0..acedc5a84e4d7 100644 --- a/net/ipv6/ila/ila_common.c +++ b/net/ipv6/ila/ila_common.c @@ -85,6 +85,7 @@ static void ila_csum_adjust_transport(struct sk_buff *skb, struct tcphdr *th = (struct tcphdr *) (skb_network_header(skb) + nhoff); + ip6h = ipv6_hdr(skb); diff = get_csum_diff(ip6h, p); inet_proto_csum_replace_by_diff(&th->check, skb, diff, true, true); @@ -96,6 +97,7 @@ static void ila_csum_adjust_transport(struct sk_buff *skb, (skb_network_header(skb) + nhoff); if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) { + ip6h = ipv6_hdr(skb); diff = get_csum_diff(ip6h, p); inet_proto_csum_replace_by_diff(&uh->check, skb, diff, true, true); @@ -110,6 +112,7 @@ static void ila_csum_adjust_transport(struct sk_buff *skb, struct icmp6hdr *ih = (struct icmp6hdr *) (skb_network_header(skb) + nhoff); + ip6h = ipv6_hdr(skb); diff = get_csum_diff(ip6h, p); inet_proto_csum_replace_by_diff(&ih->icmp6_cksum, skb, diff, true, true); @@ -151,6 +154,9 @@ void ila_update_ipv6_locator(struct sk_buff *skb, struct ila_params *p, break; } + ip6h = ipv6_hdr(skb); + iaddr = ila_a2i(&ip6h->daddr); + /* Now change destination address */ iaddr->loc = p->locator; } -- 2.53.0