CVE-2024-27406: lib/Kconfig.debug: TEST_IOV_ITER depends on MMU
In the Linux kernel, the following vulnerability has been resolved:
lib/Kconfig.debug: TESTIOVITER depends on MMU
Trying to run the ioviter unit test on a nommu system such as the qemu kc705-nommu emulation results in a crash.
KTAP version 1 # Subtest: ioviter # module: kunitioviter 1..9 BUG: failure at mm/nommu.c:318/vmap()! Kernel panic - not syncing: BUG!
The test calls vmap() directly, but vmap() is not supported on nommu systems, causing the crash. TESTIOVITER therefore needs to depend on MMU.
Affected Software
Remediation
Event History
Frequently Asked Questions
Which systems are affected in practice?
The crash affects no-MMU Linux systems when the iov_iter KUnit test is enabled and run. The reported example is qemu kc705-nommu emulation.
What must happen for the crash to occur?
A local user or process must run the iov_iter unit test on a no-MMU system. The test directly calls vmap(), which is unsupported without an MMU and causes a kernel panic.
Is a default runtime configuration affected?
The issue is tied to the TEST_IOV_ITER configuration option and execution of its KUnit test. The provided information does not indicate that ordinary kernel operation triggers the crash.
What can be done before applying the patch?
Do not enable or run TEST_IOV_ITER on no-MMU systems. The fix makes TEST_IOV_ITER depend on MMU, preventing this unsupported test configuration.