Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
fs/proc: fix softlockup in __read_vmcore (part 2)
Since commit 5cbcb62dddf5 (“fs/proc: fix softlockup in __read_vmcore”) the number of softlockups in __read_vmcore at kdump time have gone down, but they still happen sometimes.
In a memory constrained environment like the kdump image, a softlockup is not just a harmless message, but it can interfere with things like RCU freeing memory, causing the crashdump to get stuck.
The second loop in __read_vmcore has a lot more opportunities for natural sleep points, like scheduling out while waiting for a data write to happen, but apparently that is not always enough.
Add a cond_resched() to the second loop in __read_vmcore to (hopefully) get rid of the softlockups.
Details
- Affected product:
- AlmaLinux 9.2 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS
- Affected packages:
- linux @ 4.15.0 (+2 more)
In the Linux kernel, the following vulnerability has been resolved:
fs/proc: fix softlockup in __read_vmcore (part 2)
Since commit 5cbcb62dddf5 (“fs/proc: fix softlockup in __read_vmcore”) the number of softlockups in __read_vmcore at kdump time have gone down, but they still happen sometimes.
In a memory constrained environment like the kdump image, a softlockup is not just a harmless message, but it can interfere with things like RCU freeing memory, causing the crashdump to get stuck.
The second loop in __read_vmcore has a lot more opportunities for natural sleep points, like scheduling out while waiting for a data write to happen, but apparently that is not always enough.
Add a cond_resched() to the second loop in __read_vmcore to (hopefully) get rid of the softlockups.