Linux Kernel Softlockup Vulnerability in __read_vmcore

A softlockup vulnerability has been identified in the Linux kernel's __read_vmcore function, particularly during kdump operations. This issue arises in memory-constrained environments, where such softlockups can disrupt critical processes like RCU memory management, causing crash dumps to freeze. Although recent changes have reduced the frequency of these softlockups, they still occur sporadically. The vulnerability stems from the second loop in __read_vmcore, which, despite having more natural sleep points, can still lead to prolonged execution times.

Impact

The softlockup can interfere with RCU memory freeing processes, causing kdump crash dumps to become unresponsive.

Remediation

The vulnerability has been addressed by adding a cond_resched() call to the second loop in __read_vmcore, which is expected to eliminate the softlockup issue.