Linux Kernel Soft Lockup Vulnerability in XFRM Packet Re-injection

A vulnerability in the Linux kernel's XFRM (IPsec) module has been addressed, which caused a soft lockup by improperly handling transport-mode packet re-injection. This issue was observed during the 'tcp6-multi-diffip11' stress test of the LTP test suite, where CPU #0 became unresponsive for 22 seconds. The root cause was the use of a tasklet for packet re-injection, which led to excessive processing time for TCP transmission. The vulnerability affected Linux kernel versions prior to 6.0.0-rc6.

Impact

The vulnerability caused a soft lockup, where a CPU core became unresponsive for an extended period, disrupting normal processing and potentially leading to degraded system performance.

Reproduction

The vulnerability can be reproduced by running the 'tcp6-multi-diffip11' stress test case from the LTP test suite on a Linux kernel version prior to 6.0.0-rc6. This test case will trigger the XFRM packet re-injection process, which, under the vulnerable configuration, will cause a soft lockup on the CPU.

Remediation

Users can upgrade to Linux kernel version 6.0.0-rc6 or later, where this vulnerability has been fixed.