CVE-2025-21858 Information

Mar 13, 2025 cve

Description

In the Linux kernel the following vulnerability has been resolved:

geneve: Fix use-after-free in geneve_find_dev().

syzkaller reported a use-after-free in geneve_find_dev() [0] without repro.

geneve_configure() links struct geneve_dev.next to net_generic(net geneve_net_id)->geneve_list.

The net here could differ from dev_net(dev) if IFLA_NET_NS_PID IFLA_NET_NS_FD or IFLA_TARGET_NETNSID is set.

When dev_net(dev) is dismantled geneve_exit_batch_rtnl() finally calls unregister_netdevice_queue() for each dev in the netns and later the dev is freed.

However its geneve_dev.next is still linked to the backend UDP socket netns.

Then use-after-free will occur when another geneve dev is created in the netns.

Let’s call geneve_dellink() instead in geneve_destroy_tunnels().

[0]: BUG: KASAN: slab-use-after-free in geneve_find_dev drivers/net/geneve.c:1295 [inline] BUG: KASAN: slab-use-after-free in geneve_configure+0x234/0x858 drivers/net/geneve.c:1343 Read of size 2 at addr ffff000054d6ee24 by task syz.1.4029/13441

CPU: 1 UID: 0 PID: 13441 Comm: syz.1.4029 Not tainted 6.13.0-g0ad9617c78ac 24 dc35ca22c79fb82e8e7bc5c9c9adafea898b1e3d Hardware name: linuxdummy-virt (DT) Call trace: show_stack+0x38/0x50 arch/arm64/kernel/stacktrace.c:466 (C) __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xbc/0x108 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x16c/0x6f0 mm/kasan/report.c:489 kasan_report+0xc0/0x120 mm/kasan/report.c:602 __asan_report_load2_noabort+0x20/0x30 mm/kasan/report_generic.c:379 geneve_find_dev drivers/net/geneve.c:1295 [inline] geneve_configure+0x234/0x858 drivers/net/geneve.c:1343 geneve_newlink+0xb8/0x128 drivers/net/geneve.c:1634 rtnl_newlink_create+0x23c/0x868 net/core/rtnetlink.c:3795 __rtnl_newlink net/core/rtnetlink.c:3906 [inline] rtnl_newlink+0x1054/0x1630 net/core/rtnetlink.c:4021 rtnetlink_rcv_msg+0x61c/0x918 net/core/rtnetlink.c:6911 netlink_rcv_skb+0x1dc/0x398 net/netlink/af_netlink.c:2543 rtnetlink_rcv+0x34/0x50 net/core/rtnetlink.c:6938 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0x618/0x838 net/netlink/af_netlink.c:1348 netlink_sendmsg+0x5fc/0x8b0 net/netlink/af_netlink.c:1892 sock_sendmsg_nosec net/socket.c:713 [inline] __sock_sendmsg net/socket.c:728 [inline] ____sys_sendmsg+0x410/0x6f8 net/socket.c:2568 ___sys_sendmsg+0x178/0x1d8 net/socket.c:2622 __sys_sendmsg net/socket.c:2654 [inline] __do_sys_sendmsg net/socket.c:2659 [inline] __se_sys_sendmsg net/socket.c:2657 [inline] __arm64_sys_sendmsg+0x12c/0x1c8 net/socket.c:2657 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x90/0x278 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x13c/0x250 arch/arm64/kernel/syscall.c:132 do_el0_svc+0x54/0x70 arch/arm64/kernel/syscall.c:151 el0_svc+0x4c/0xa8 arch/arm64/kernel/entry-common.c:744 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:762 el0t_64_sync+0x198/0x1a0 arch/arm64/kernel/entry.S:600

truncated—

Reference

https://git.kernel.org/stable/c/3ce92ca990cfac88a87c61df3cc0b5880e688ecf https://git.kernel.org/stable/c/788dbca056a8783ec063da3c9d49a3a71c76c283 https://git.kernel.org/stable/c/904e746b2e7fa952ab8801b303ce826a63153d78 https://git.kernel.org/stable/c/9593172d93b9f91c362baec4643003dc29802929 https://git.kernel.org/stable/c/da9b0ae47f084014b1e4b3f31f70a0defd047ff3

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