Re: [5.15] Please apply 'selftest/lkdtm: Skip stack-entropy test if lkdtm is not available'

On Fri, Feb 17, 2023 at 02:17:05PM -0800, Andrew Paniakin wrote:

commit 90091c367e74d5b58d9ebe979cc363f7468f58d3 upstream.

This patch fixes the stack-entropy.sh test to exit gracefully when the LKDTM is not available. Test will hang otherwise as reported in [1].

Applicability of this fix to other LTS kernels:

• 4.14: No lkdtm selftest
• 4.19: No lkdtm selftest
• 5.4: No lkdtm selftests
• 5.10: Inital selftest version introduced in 46d1a0f03d661 ("selftests/lkdtm: Add tests for LKDTM targets") is a single script which has the LKDTM availability check
• 6.1: Fix applied

This patch applies cleanly to stable-5.15 tree. Updated test was executed in Qemu VM with different kernels:

• CONFIG_LKDTM not enabled. Test finished with status SKIP.
• CONFIG_LKDTM enabled. Test failed (but not hanged) with error 'Stack entropy is low'.
• CONFIG_LKDTM enabled and randomize_kstack_offset=on boot argument provided. Test succeed.

[1] https://lore.kernel.org/lkml/2836f48a-d4e2-7f00-f06c-9f556fbd6332@linuxfound...

Now queued up, thanks.

greg k-h