CVE-2024-42096

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

x86: stop playing stack games in profile_pc()

The 'profile_pc()' function is used for timer-based profiling, which

isn't really all that relevant any more to begin with, but it also ends

up making assumptions based on the stack layout that aren't necessarily

valid.

Basically, the code tries to account the time spent in spinlocks to the

caller rather than the spinlock, and while I support that as a concept,

it's not worth the code complexity or the KASAN warnings when no serious

profiling is done using timers anyway these days.

And the code really does depend on stack layout that is only true in the

simplest of cases. We've lost the comment at some point (I think when

the 32-bit and 64-bit code was unified), but it used to say:

Assume the lock function has either no stack frame or a copy

of eflags from PUSHF.

which explains why it just blindly loads a word or two straight off the

stack pointer and then takes a

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References