user/sven/linux.git/kernel/kcsan, branch v5.10.177

kcsan: avoid passing -g for test

2023-04-05T09:23:44Z

[ Upstream commit 5eb39cde1e2487ba5ec1802dc5e58a77e700d99e ] Nathan reported that when building with GNU as and a version of clang that defaults to DWARF5, the assembler will complain with: Error: non-constant .uleb128 is not supported This is because `-g` defaults to the compiler debug info default. If the assembler does not support some of the directives used, the above errors occur. To fix, remove the explicit passing of `-g`. All the test wants is that stack traces print valid function names, and debug info is not required for that. (I currently cannot recall why I added the explicit `-g`.) Link: https://lkml.kernel.org/r/20230316224705.709984-2-elver@google.com Fixes: 1fe84fd4a402 ("kcsan: Add test suite") Signed-off-by: Marco Elver Reported-by: Nathan Chancellor Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

kernel: kcsan: kcsan_test: build without structleak plugin

2023-04-05T09:23:43Z

[ Upstream commit 6fcd4267a840d0536b8e5334ad5f31e4105fce85 ] Building kcsan_test with structleak plugin enabled makes the stack frame size to grow. kernel/kcsan/kcsan_test.c:704:1: error: the frame size of 3296 bytes is larger than 2048 bytes [-Werror=frame-larger-than=] Turn off the structleak plugin checks for kcsan_test. Link: https://lkml.kernel.org/r/20221128104358.2660634-1-anders.roxell@linaro.org Signed-off-by: Anders Roxell Suggested-by: Arnd Bergmann Acked-by: Marco Elver Cc: Arnd Bergmann Cc: David Gow Cc: Jason A. Donenfeld Cc: Kees Cook Signed-off-by: Andrew Morton Stable-dep-of: 5eb39cde1e24 ("kcsan: avoid passing -g for test") Signed-off-by: Sasha Levin

panic: Consolidate open-coded panic_on_warn checks

2023-02-01T07:23:20Z

commit 79cc1ba7badf9e7a12af99695a557e9ce27ee967 upstream. Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll their own warnings, and each check "panic_on_warn". Consolidate this into a single function so that future instrumentation can be added in a single location. Cc: Marco Elver Cc: Dmitry Vyukov Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Juri Lelli Cc: Vincent Guittot Cc: Dietmar Eggemann Cc: Steven Rostedt Cc: Ben Segall Cc: Mel Gorman Cc: Daniel Bristot de Oliveira Cc: Valentin Schneider Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Vincenzo Frascino Cc: Andrew Morton Cc: David Gow Cc: tangmeng Cc: Jann Horn Cc: Shuah Khan Cc: Petr Mladek Cc: "Paul E. McKenney" Cc: Sebastian Andrzej Siewior Cc: "Guilherme G. Piccoli" Cc: Tiezhu Yang Cc: kasan-dev@googlegroups.com Cc: linux-mm@kvack.org Reviewed-by: Luis Chamberlain Signed-off-by: Kees Cook Reviewed-by: Marco Elver Reviewed-by: Andrey Konovalov Link: https://lore.kernel.org/r/20221117234328.594699-4-keescook@chromium.org Signed-off-by: Eric Biggers Signed-off-by: Sasha Levin

kcsan: test: don't put the expect array on the stack

2023-02-01T07:23:16Z

[ Upstream commit 5b24ac2dfd3eb3e36f794af3aa7f2828b19035bd ] Size of the 'expect' array in the __report_matches is 1536 bytes, which is exactly the default frame size warning limit of the xtensa architecture. As a result allmodconfig xtensa kernel builds with the gcc that does not support the compiler plugins (which otherwise would push the said warning limit to 2K) fail with the following message: kernel/kcsan/kcsan_test.c:257:1: error: the frame size of 1680 bytes is larger than 1536 bytes Fix it by dynamically allocating the 'expect' array. Signed-off-by: Max Filippov Reviewed-by: Marco Elver Tested-by: Marco Elver Signed-off-by: Sasha Levin

kcsan: Instrument memcpy/memset/memmove with newer Clang

2023-01-14T09:16:28Z

commit 7c201739beef1a586d806463f1465429cdce34c5 upstream. With Clang version 16+, -fsanitize=thread will turn memcpy/memset/memmove calls in instrumented functions into __tsan_memcpy/__tsan_memset/__tsan_memmove calls respectively. Add these functions to the core KCSAN runtime, so that we (a) catch data races with mem* functions, and (b) won't run into linker errors with such newer compilers. Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney [ elver@google.com: adjust check_access() call for v5.15 and earlier. ] Signed-off-by: Greg Kroah-Hartman

kcsan: Fix debugfs initcall return type

2021-05-26T10:06:54Z

commit 976aac5f882989e4f6c1b3a7224819bf0e801c6a upstream. clang with CONFIG_LTO_CLANG points out that an initcall function should return an 'int' due to the changes made to the initcall macros in commit 3578ad11f3fb ("init: lto: fix PREL32 relocations"): kernel/kcsan/debugfs.c:274:15: error: returning 'void' from a function with incompatible result type 'int' late_initcall(kcsan_debugfs_init); ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~ include/linux/init.h:292:46: note: expanded from macro 'late_initcall' #define late_initcall(fn) __define_initcall(fn, 7) Fixes: e36299efe7d7 ("kcsan, debugfs: Move debugfs file creation out of early init") Cc: stable Reviewed-by: Greg Kroah-Hartman Reviewed-by: Marco Elver Reviewed-by: Nathan Chancellor Reviewed-by: Miguel Ojeda Signed-off-by: Arnd Bergmann Signed-off-by: Paul E. McKenney Signed-off-by: Greg Kroah-Hartman

kcsan, debugfs: Move debugfs file creation out of early init

2021-05-11T12:47:33Z

commit e36299efe7d749976fbdaaf756dee6ef32543c2c upstream. Commit 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized") forbids creating new debugfs files until debugfs is fully initialized. This means that KCSAN's debugfs file creation, which happened at the end of __init(), no longer works. And was apparently never supposed to work! However, there is no reason to create KCSAN's debugfs file so early. This commit therefore moves its creation to a late_initcall() callback. Cc: "Rafael J. Wysocki" Cc: stable Fixes: 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized") Reviewed-by: Greg Kroah-Hartman Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney Signed-off-by: Greg Kroah-Hartman

kcsan: Rewrite kcsan_prandom_u32_max() without prandom_u32_state()

2021-03-04T10:37:37Z

[ Upstream commit 71a076f4a61a6c779794ad286f356b39725edc3b ] Rewrite kcsan_prandom_u32_max() to not depend on code that might be instrumented, removing any dependency on lib/random32.c. The rewrite implements a simple linear congruential generator, that is sufficient for our purposes (for udelay() and skip_watch counter randomness). The initial motivation for this was to allow enabling KCSAN for kernel/sched (remove KCSAN_SANITIZE := n from kernel/sched/Makefile), with CONFIG_DEBUG_PREEMPT=y. Without this change, we could observe recursion: check_access() [via instrumentation] kcsan_setup_watchpoint() reset_kcsan_skip() kcsan_prandom_u32_max() get_cpu_var() preempt_disable() preempt_count_add() [in kernel/sched/core.c] check_access() [via instrumentation] Note, while this currently does not affect an unmodified kernel, it'd be good to keep a KCSAN kernel working when KCSAN_SANITIZE := n is removed from kernel/sched/Makefile to permit testing scheduler code with KCSAN if desired. Fixes: cd290ec24633 ("kcsan: Use tracing-safe version of prandom") Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney Signed-off-by: Sasha Levin

kernel/: fix repeated words in comments

2020-10-16T18:11:19Z

Fix multiple occurrences of duplicated words in kernel/. Fix one typo/spello on the same line as a duplicate word. Change one instance of "the the" to "that the". Otherwise just drop one of the repeated words. Signed-off-by: Randy Dunlap Signed-off-by: Andrew Morton Link: https://lkml.kernel.org/r/98202fa6-8919-ef63-9efe-c0fad5ca7af1@infradead.org Signed-off-by: Linus Torvalds

kcsan: Use tracing-safe version of prandom

2020-08-31T04:50:13Z

In the core runtime, we must minimize any calls to external library functions to avoid any kind of recursion. This can happen even though instrumentation is disabled for called functions, but tracing is enabled. Most recently, prandom_u32() added a tracepoint, which can cause problems for KCSAN even if the rcuidle variant is used. For example: kcsan -> prandom_u32() -> trace_prandom_u32_rcuidle -> srcu_read_lock_notrace -> __srcu_read_lock -> kcsan ... While we could disable KCSAN in kcsan_setup_watchpoint(), this does not solve other unexpected behaviour we may get due recursing into functions that may not be tolerant to such recursion: __srcu_read_lock -> kcsan -> ... -> __srcu_read_lock Therefore, switch to using prandom_u32_state(), which is uninstrumented, and does not have a tracepoint. Link: https://lkml.kernel.org/r/20200821063043.1949509-1-elver@google.com Link: https://lkml.kernel.org/r/20200820172046.GA177701@elver.google.com Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney