user/sven/linux.git/kernel/module/main.c, branch v6.1.12

module: Don't wait for GOING modules

2023-02-01T07:34:37Z

commit 0254127ab977e70798707a7a2b757c9f3c971210 upstream. During a system boot, it can happen that the kernel receives a burst of requests to insert the same module but loading it eventually fails during its init call. For instance, udev can make a request to insert a frequency module for each individual CPU when another frequency module is already loaded which causes the init function of the new module to return an error. Since commit 6e6de3dee51a ("kernel/module.c: Only return -EEXIST for modules that have finished loading"), the kernel waits for modules in MODULE_STATE_GOING state to finish unloading before making another attempt to load the same module. This creates unnecessary work in the described scenario and delays the boot. In the worst case, it can prevent udev from loading drivers for other devices and might cause timeouts of services waiting on them and subsequently a failed boot. This patch attempts a different solution for the problem 6e6de3dee51a was trying to solve. Rather than waiting for the unloading to complete, it returns a different error code (-EBUSY) for modules in the GOING state. This should avoid the error situation that was described in 6e6de3dee51a (user space attempting to load a dependent module because the -EEXIST error code would suggest to user space that the first module had been loaded successfully), while avoiding the delay situation too. This has been tested on linux-next since December 2022 and passes all kmod selftests except test 0009 with module compression enabled but it has been confirmed that this issue has existed and has gone unnoticed since prior to this commit and can also be reproduced without module compression with a simple usleep(5000000) on tools/modprobe.c [0]. These failures are caused by hitting the kernel mod_concurrent_max and can happen either due to a self inflicted kernel module auto-loead DoS somehow or on a system with large CPU count and each CPU count incorrectly triggering many module auto-loads. Both of those issues need to be fixed in-kernel. [0] https://lore.kernel.org/all/Y9A4fiobL6IHp%2F%2FP@bombadil.infradead.org/ Fixes: 6e6de3dee51a ("kernel/module.c: Only return -EEXIST for modules that have finished loading") Co-developed-by: Martin Wilck Signed-off-by: Martin Wilck Signed-off-by: Petr Pavlu Cc: stable@vger.kernel.org Reviewed-by: Petr Mladek [mcgrof: enhance commit log with testing and kmod test result interpretation ] Signed-off-by: Luis Chamberlain Signed-off-by: Greg Kroah-Hartman

Merge tag 'driver-core-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2022-10-08T00:04:10Z

Pull driver core updates from Greg KH: "Here is the big set of driver core and debug printk changes for 6.1-rc1. Included in here is: - dynamic debug updates for the core and the drm subsystem. The drm changes have all been acked by the relevant maintainers - kernfs fixes for syzbot reported problems - kernfs refactors and updates for cgroup requirements - magic number cleanups and removals from the kernel tree (they were not being used and they really did not actually do anything) - other tiny cleanups All of these have been in linux-next for a while with no reported issues" * tag 'driver-core-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (74 commits) docs: filesystems: sysfs: Make text and code for ->show() consistent Documentation: NBD_REQUEST_MAGIC isn't a magic number a.out: restore CMAGIC device property: Add const qualifier to device_get_match_data() parameter drm_print: add _ddebug descriptor to drm_*dbg prototypes drm_print: prefer bare printk KERN_DEBUG on generic fn drm_print: optimize drm_debug_enabled for jump-label drm-print: add drm_dbg_driver to improve namespace symmetry drm-print.h: include dyndbg header drm_print: wrap drm_*_dbg in dyndbg descriptor factory macro drm_print: interpose drm_*dbg with forwarding macros drm: POC drm on dyndbg - use in core, 2 helpers, 3 drivers. drm_print: condense enum drm_debug_category debugfs: use DEFINE_SHOW_ATTRIBUTE to define debugfs_regset32_fops driver core: use IS_ERR_OR_NULL() helper in device_create_groups_vargs() Documentation: ENI155_MAGIC isn't a magic number Documentation: NBD_REPLY_MAGIC isn't a magic number nbd: remove define-only NBD_MAGIC, previously magic number Documentation: FW_HEADER_MAGIC isn't a magic number Documentation: EEPROM_MAGIC_VALUE isn't a magic number ...

cfi: Switch to -fsanitize=kcfi

2022-09-26T17:13:13Z

Switch from Clang's original forward-edge control-flow integrity implementation to -fsanitize=kcfi, which is better suited for the kernel, as it doesn't require LTO, doesn't use a jump table that requires altering function references, and won't break cross-module function address equality. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor Acked-by: Peter Zijlstra (Intel) Tested-by: Peter Zijlstra (Intel) Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220908215504.3686827-6-samitolvanen@google.com

cfi: Remove CONFIG_CFI_CLANG_SHADOW

2022-09-26T17:13:12Z

In preparation to switching to -fsanitize=kcfi, remove support for the CFI module shadow that will no longer be needed. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor Acked-by: Peter Zijlstra (Intel) Tested-by: Peter Zijlstra (Intel) Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220908215504.3686827-4-samitolvanen@google.com

Merge 6.0-rc5 into driver-core-next

2022-09-12T14:51:22Z

We need the driver core and debugfs changes in this branch. Signed-off-by: Greg Kroah-Hartman

kernel/module: add __dyndbg_classes section

2022-09-07T15:04:49Z

Add __dyndbg_classes section, using __dyndbg as a model. Use it: vmlinux.lds.h: KEEP the new section, which also silences orphan section warning on loadable modules. Add (__start_/__stop_)__dyndbg_classes linker symbols for the c externs (below). kernel/module/main.c: - fill new fields in find_module_sections(), using section_objs() - extend callchain prototypes to pass classes, length load_module(): pass new info to dynamic_debug_setup() dynamic_debug_setup(): new params, pass through to ddebug_add_module() dynamic_debug.c: - add externs to the linker symbols. ddebug_add_module(): - It currently builds a debug_table, and *will* find and attach classes. dynamic_debug_init(): - add class fields to the _ddebug_info cursor var: di. Signed-off-by: Jim Cromie Link: https://lore.kernel.org/r/20220904214134.408619-16-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman

dyndbg: gather __dyndbg[] state into struct _ddebug_info

2022-09-07T15:04:48Z

This new struct composes the linker provided (vector,len) section, and provides a place to add other __dyndbg[] state-data later: descs - the vector of descriptors in __dyndbg section. num_descs - length of the data/section. Use it, in several different ways, as follows: In lib/dynamic_debug.c: ddebug_add_module(): Alter params-list, replacing 2 args (array,index) with a struct _ddebug_info * containing them both, with room for expansion. This helps future-proof the function prototype against the looming addition of class-map info into the dyndbg-state, by providing a place to add more member fields later. NB: later add static struct _ddebug_info builtins_state declaration, not needed yet. ddebug_add_module() is called in 2 contexts: In dynamic_debug_init(), declare, init a struct _ddebug_info di auto-var to use as a cursor. Then iterate over the prdbg blocks of the builtin modules, and update the di cursor before calling _add_module for each. Its called from kernel/module/main.c:load_info() for each loaded module: In internal.h, alter struct load_info, replacing the dyndbg array,len fields with an embedded _ddebug_info containing them both; and populate its members in find_module_sections(). The 2 calling contexts differ in that _init deals with contiguous subranges of __dyndbgs[] section, packed together, while loadable modules are added one at a time. So rename ddebug_add_module() into outer/__inner fns, call __inner from _init, and provide the offset into the builtin __dyndbgs[] where the module's prdbgs reside. The cursor provides start, len of the subrange for each. The offset will be used later to pack the results of builtin __dyndbg_sites[] de-duplication, and is 0 and unneeded for loadable modules, Note: kernel/module/main.c includes for struct _ddeubg_info. This might be prone to include loops, since its also included by printk.h. Nothing has broken in robot-land on this. cc: Luis Chamberlain Signed-off-by: Jim Cromie Link: https://lore.kernel.org/r/20220904214134.408619-12-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman

module: kunit: Load .kunit_test_suites section when CONFIG_KUNIT=m

2022-08-15T19:51:07Z

The new KUnit module handling has KUnit test suites listed in a .kunit_test_suites section of each module. This should be loaded when the module is, but at the moment this only happens if KUnit is built-in. Also load this when KUnit is enabled as a module: it'll not be usable unless KUnit is loaded, but such modules are likely to depend on KUnit anyway, so it's unlikely to ever be loaded needlessly. Fixes: 3d6e44623841 ("kunit: unify module and builtin suite definitions") Signed-off-by: David Gow Reviewed-by: Brendan Higgins Tested-by: Geert Uytterhoeven Signed-off-by: Shuah Khan

Merge tag 'modules-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

2022-08-08T21:12:19Z

Pull module updates from Luis Chamberlain: "For the 6.0 merge window the modules code shifts to cleanup and minor fixes effort. This becomes much easier to do and review now due to the code split to its own directory from effort on the last kernel release. I expect to see more of this with time and as we expand on test coverage in the future. The cleanups and fixes come from usual suspects such as Christophe Leroy and Aaron Tomlin but there are also some other contributors. One particular minor fix worth mentioning is from Helge Deller, where he spotted a *forever* incorrect natural alignment on both ELF section header tables: * .altinstructions * __bug_table sections A lot of back and forth went on in trying to determine the ill effects of this misalignment being present for years and it has been determined there should be no real ill effects unless you have a buggy exception handler. Helge actually hit one of these buggy exception handlers on parisc which is how he ended up spotting this issue. When implemented correctly these paths with incorrect misalignment would just mean a performance penalty, but given that we are dealing with alternatives on modules and with the __bug_table (where info regardign BUG()/WARN() file/line information associated with it is stored) this really shouldn't be a big deal. The only other change with mentioning is the kmap() with kmap_local_page() and my only concern with that was on what is done after preemption, but the virtual addresses are restored after preemption. This is only used on module decompression. This all has sit on linux-next for a while except the kmap stuff which has been there for 3 weeks" * tag 'modules-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: module: Replace kmap() with kmap_local_page() module: Show the last unloaded module's taint flag(s) module: Use strscpy() for last_unloaded_module module: Modify module_flags() to accept show_state argument module: Move module's Kconfig items in kernel/module/ MAINTAINERS: Update file list for module maintainers module: Use vzalloc() instead of vmalloc()/memset(0) modules: Ensure natural alignment for .altinstructions and __bug_table sections module: Increase readability of module_kallsyms_lookup_name() module: Fix ERRORs reported by checkpatch.pl module: Add support for default value for module async_probe

Merge tag 'linux-kselftest-kunit-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2022-08-03T02:34:45Z

Pull KUnit updates from Shuah Khan: "This consists of several fixes and an important feature to discourage running KUnit tests on production systems. Running tests on a production system could leave the system in a bad state. Summary: - Add a new taint type, TAINT_TEST to signal that a test has been run. This should discourage people from running these tests on production systems, and to make it easier to tell if tests have been run accidentally (by loading the wrong configuration, etc) - Several documentation and tool enhancements and fixes" * tag 'linux-kselftest-kunit-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (29 commits) Documentation: KUnit: Fix example with compilation error Documentation: kunit: Add CLI args for kunit_tool kcsan: test: Add a .kunitconfig to run KCSAN tests kunit: executor: Fix a memory leak on failure in kunit_filter_tests clk: explicitly disable CONFIG_UML_PCI_OVER_VIRTIO in .kunitconfig mmc: sdhci-of-aspeed: test: Use kunit_test_suite() macro nitro_enclaves: test: Use kunit_test_suite() macro thunderbolt: test: Use kunit_test_suite() macro kunit: flatten kunit_suite*** to kunit_suite** in .kunit_test_suites kunit: unify module and builtin suite definitions selftest: Taint kernel when test module loaded module: panic: Taint the kernel when selftest modules load Documentation: kunit: fix example run_kunit func to allow spaces in args Documentation: kunit: Cleanup run_wrapper, fix x-ref kunit: test.h: fix a kernel-doc markup kunit: tool: Enable virtio/PCI by default on UML kunit: tool: make --kunitconfig repeatable, blindly concat kunit: add coverage_uml.config to enable GCOV on UML kunit: tool: refactor internal kconfig handling, allow overriding kunit: tool: introduce --qemu_args ...