High · published October 6, 2026
In the Linux kernel, the following vulnerability has been resolved:
xfrm: hold net_device reference under RCU in bundle creation
xfrm_bundle_create() and xfrm_create_dummy_bundle() read dst->dev into
a local pointer without taking a device reference, then pass it to
xfrm_fill_dst(). A concurrent RTM_DELLINK replaces dst->dev via
dst_dev_put() and frees the old net_device, causing a use-after-free
when xfrm6_fill_dst() later dereferences the stale dev pointer.
BUG: KASAN: slab-use-after-free in xfrm6_fill_dst+0x82c/0x860
(net/ipv6/xfrm6_policy.c:86 netdev_hold())
Read of size 8 at addr ffff8880142fe588 by task exploit/153
Call Trace:
xfrm6_fill_dst+0x82c/0x860
xfrm_resolve_and_create_bundle+0x21d4/0x2bd0
xfrm_lookup_with_ifid+0x485/0x1640
ip6_dst_lookup_flow+0x19b/0x1e0
udpv6_sendmsg+0x1443/0x2dd0
Fix this by reading dst->dev via dst_dev_rcu() and keeping the RCU
read-side critical section active until xfrm_fill_dst() has taken the
required device references.