CVE-2026-23273
Undergoing Analysis
Undergoing Analysis - In Progress
Use-After-Free Race Condition in Linux Kernel macvlan Network Driver
Publication date: 2026-03-20
Last updated on: 2026-05-22
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
macvlan: observe an RCU grace period in macvlan_common_newlink() error path
valis reported that a race condition still happens after my prior patch.
macvlan_common_newlink() might have made @dev visible before
detecting an error, and its caller will directly call free_netdev(dev).
We must respect an RCU period, either in macvlan or the core networking
stack.
After adding a temporary mdelay(1000) in macvlan_forward_source_one()
to open the race window, valis repro was:
ip link add p1 type veth peer p2
ip link set address 00:00:00:00:00:20 dev p1
ip link set up dev p1
ip link set up dev p2
ip link add mv0 link p2 type macvlan mode source
(ip link add invalid% link p2 type macvlan mode source macaddr add
00:00:00:00:00:20 &) ; sleep 0.5 ; ping -c1 -I p1 1.2.3.4
PING 1.2.3.4 (1.2.3.4): 56 data bytes
RTNETLINK answers: Invalid argument
BUG: KASAN: slab-use-after-free in macvlan_forward_source
(drivers/net/macvlan.c:408 drivers/net/macvlan.c:444)
Read of size 8 at addr ffff888016bb89c0 by task e/175
CPU: 1 UID: 1000 PID: 175 Comm: e Not tainted 6.19.0-rc8+ #33 NONE
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl (lib/dump_stack.c:123)
print_report (mm/kasan/report.c:379 mm/kasan/report.c:482)
? macvlan_forward_source (drivers/net/macvlan.c:408 drivers/net/macvlan.c:444)
kasan_report (mm/kasan/report.c:597)
? macvlan_forward_source (drivers/net/macvlan.c:408 drivers/net/macvlan.c:444)
macvlan_forward_source (drivers/net/macvlan.c:408 drivers/net/macvlan.c:444)
? tasklet_init (kernel/softirq.c:983)
macvlan_handle_frame (drivers/net/macvlan.c:501)
Allocated by task 169:
kasan_save_stack (mm/kasan/common.c:58)
kasan_save_track (./arch/x86/include/asm/current.h:25
mm/kasan/common.c:70 mm/kasan/common.c:79)
__kasan_kmalloc (mm/kasan/common.c:419)
__kvmalloc_node_noprof (./include/linux/kasan.h:263 mm/slub.c:5657
mm/slub.c:7140)
alloc_netdev_mqs (net/core/dev.c:12012)
rtnl_create_link (net/core/rtnetlink.c:3648)
rtnl_newlink (net/core/rtnetlink.c:3830 net/core/rtnetlink.c:3957
net/core/rtnetlink.c:4072)
rtnetlink_rcv_msg (net/core/rtnetlink.c:6958)
netlink_rcv_skb (net/netlink/af_netlink.c:2550)
netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)
netlink_sendmsg (net/netlink/af_netlink.c:1894)
__sys_sendto (net/socket.c:727 net/socket.c:742 net/socket.c:2206)
__x64_sys_sendto (net/socket.c:2209)
do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:131)
Freed by task 169:
kasan_save_stack (mm/kasan/common.c:58)
kasan_save_track (./arch/x86/include/asm/current.h:25
mm/kasan/common.c:70 mm/kasan/common.c:79)
kasan_save_free_info (mm/kasan/generic.c:587)
__kasan_slab_free (mm/kasan/common.c:287)
kfree (mm/slub.c:6674 mm/slub.c:6882)
rtnl_newlink (net/core/rtnetlink.c:3845 net/core/rtnetlink.c:3957
net/core/rtnetlink.c:4072)
rtnetlink_rcv_msg (net/core/rtnetlink.c:6958)
netlink_rcv_skb (net/netlink/af_netlink.c:2550)
netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)
netlink_sendmsg (net/netlink/af_netlink.c:1894)
__sys_sendto (net/socket.c:727 net/socket.c:742 net/socket.c:2206)
__x64_sys_sendto (net/socket.c:2209)
do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:131)
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | From 6.12.70 (inc) to 6.12.75 (exc) |
| linux | linux_kernel | From 5.10.250 (inc) to 5.10.252 (exc) |
| linux | linux_kernel | From 5.15.200 (inc) to 5.15.202 (exc) |
| linux | linux_kernel | From 6.1.163 (inc) to 6.1.165 (exc) |
| linux | linux_kernel | From 6.18.10 (inc) to 6.18.14 (exc) |
| linux | linux_kernel | From 6.19.1 (inc) to 6.19.4 (exc) |
| linux | linux_kernel | From 6.6.124 (inc) to 6.6.128 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-416 | The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. |
