CVE-2022-49888

/// Technical description

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

arm64: entry: avoid kprobe recursion

The cortex_a76_erratum_1463225_debug_handler() function is called when

handling debug exceptions (and synchronous exceptions from BRK

instructions), and so is called when a probed function executes. If the

compiler does not inline cortex_a76_erratum_1463225_debug_handler(), it

can be probed.

If cortex_a76_erratum_1463225_debug_handler() is probed, any debug

exception or software breakpoint exception will result in recursive

exceptions leading to a stack overflow. This can be triggered with the

ftrace multiple_probes selftest, and as per the example splat below.

This is a regression caused by commit:

6459b8469753e9fe ("arm64: entry: consolidate Cortex-A76 erratum 1463225 workaround")

... which removed the NOKPROBE_SYMBOL() annotation associated with the

function.

My intent was that cortex_a76_erratum_1463225_debug_handler() would be

inlined into its caller, el1_dbg(), which

/// 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