CVE-2026-98278net: remove WARN_ON_ONCE() from the dev_fill_forward_path() loop check

Official description

In the Linux kernel, the following vulnerability has been resolved: net: remove WARN_ON_ONCE() from the dev_fill_forward_path() loop check ipip_fill_forward_path() and ip6_tnl_fill_forward_path() look up the route to the tunnel's remote endpoint and set ctx->dev to its device, which is the tunnel itself when that route resolves back to the tunnel. dev_fill_forward_path() then makes no progress and trips WARN_ON_ONCE(last_dev == ctx->dev) as soon as a flowtable tries to offload a flow through the tunnel. That routing loop is a configuration any CAP_NET_ADMIN user can set up, and ip_tunnel_xmit() and ip6_tnl_xmit() already treat it as a tx error, so remove the warning and just fail the walk, as commit 008e7a7c293b ("net: remove WARN_ON_ONCE when accessing forward path array") did for the path stack overflow.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/d8eb177632dacda28bc6130c2105afbf5b791eb0
• https://git.kernel.org/stable/c/150dba2c69e93302af24a0c868eebe4871e2e107