linux/net/ipv6/ila
Michael Bommarito 92d3817649 ila: reload IPv6 header after pskb_may_pull in checksum adjust
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()
uses ip6h (and the iaddr derived from it) again after the csum-adjust
call and additionally writes the new locator through that 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 after each pskb_may_pull() in ila_csum_adjust_transport()
before the csum-diff read. In ila_update_ipv6_locator() only the
ILA_CSUM_ADJUST_TRANSPORT case pulls the skb, so reload ip6h and iaddr in
that case alone before the destination-address write; the neutral-map
modes never pull and keep their cached pointers.

Fixes: 33f11d1614 ("ila: Create net/ipv6/ila directory")
Cc: stable@vger.kernel.org
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Antoine Tenart <atenart@kernel.org>
Link: https://patch.msgid.link/20260714114903.3763420-1-michael.bommarito@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-22 14:00:41 -07:00
..
ila_common.c ila: reload IPv6 header after pskb_may_pull in checksum adjust 2026-07-22 14:00:41 -07:00
ila_lwt.c ipv6: adopt dst_dev() helper 2025-07-02 14:32:30 -07:00
ila_main.c ila: call nf_unregister_net_hooks() sooner 2024-09-05 14:57:12 -07:00
ila_xlat.c Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
ila.h ila: call nf_unregister_net_hooks() sooner 2024-09-05 14:57:12 -07:00
Makefile