From 7535b832c6399b5ebfc5b53af5c51dd915ee2538 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 16 Dec 2022 12:26:57 -0800 Subject: exit: Use READ_ONCE() for all oops/warn limit reads Use a temporary variable to take full advantage of READ_ONCE() behavior. Without this, the report (and even the test) might be out of sync with the initial test. Reported-by: Peter Zijlstra Link: https://lore.kernel.org/lkml/Y5x7GXeluFmZ8E0E@hirez.programming.kicks-ass.net Fixes: 9fc9e278a5c0 ("panic: Introduce warn_limit") Fixes: d4ccd54d28d3 ("exit: Put an upper limit on how often we can oops") Cc: "Eric W. Biederman" Cc: Jann Horn Cc: Arnd Bergmann Cc: Petr Mladek Cc: Andrew Morton Cc: Luis Chamberlain Cc: Marco Elver Cc: tangmeng Cc: Sebastian Andrzej Siewior Cc: Tiezhu Yang Signed-off-by: Kees Cook --- kernel/exit.c | 6 ++++-- kernel/panic.c | 7 +++++-- 2 files changed, 9 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/exit.c b/kernel/exit.c index deffb8e4b1b2..15dc2ec80c46 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -931,6 +931,7 @@ void __noreturn make_task_dead(int signr) * Then do everything else. */ struct task_struct *tsk = current; + unsigned int limit; if (unlikely(in_interrupt())) panic("Aiee, killing interrupt handler!"); @@ -954,8 +955,9 @@ void __noreturn make_task_dead(int signr) * To make sure this can't happen, place an upper bound on how often the * kernel may oops without panic(). */ - if (atomic_inc_return(&oops_count) >= READ_ONCE(oops_limit) && oops_limit) - panic("Oopsed too often (kernel.oops_limit is %d)", oops_limit); + limit = READ_ONCE(oops_limit); + if (atomic_inc_return(&oops_count) >= limit && limit) + panic("Oopsed too often (kernel.oops_limit is %d)", limit); /* * We're taking recursive faults here in make_task_dead. Safest is to just diff --git a/kernel/panic.c b/kernel/panic.c index 54deb743b2d5..7834c9854e02 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -231,12 +231,15 @@ static void panic_print_sys_info(bool console_flush) void check_panic_on_warn(const char *origin) { + unsigned int limit; + if (panic_on_warn) panic("%s: panic_on_warn set ...\n", origin); - if (atomic_inc_return(&warn_count) >= READ_ONCE(warn_limit) && warn_limit) + limit = READ_ONCE(warn_limit); + if (atomic_inc_return(&warn_count) >= limit && limit) panic("%s: system warned too often (kernel.warn_limit is %d)", - origin, warn_limit); + origin, limit); } /** -- cgit v1.2.3 From cf8016408d880afe9c5dc495af40dc2932874e77 Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Thu, 22 Dec 2022 22:57:47 +0000 Subject: cfi: Fix CFI failure with KASAN When CFI_CLANG and KASAN are both enabled, LLVM doesn't generate a CFI type hash for asan.module_ctor functions in translation units where CFI is disabled, which leads to a CFI failure during boot when do_ctors calls the affected constructors: CFI failure at do_basic_setup+0x64/0x90 (target: asan.module_ctor+0x0/0x28; expected type: 0xa540670c) Specifically, this happens because CFI is disabled for kernel/cfi.c. There's no reason to keep CFI disabled here anymore, so fix the failure by not filtering out CC_FLAGS_CFI for the file. Note that https://reviews.llvm.org/rG3b14862f0a96 fixed the issue where LLVM didn't emit CFI type hashes for any sanitizer constructors, but now type hashes are emitted correctly for TUs that use CFI. Link: https://github.com/ClangBuiltLinux/linux/issues/1742 Fixes: 89245600941e ("cfi: Switch to -fsanitize=kcfi") Reported-by: Mark Rutland Signed-off-by: Sami Tolvanen Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20221222225747.3538676-1-samitolvanen@google.com --- kernel/Makefile | 3 --- 1 file changed, 3 deletions(-) (limited to 'kernel') diff --git a/kernel/Makefile b/kernel/Makefile index d754e0be1176..ebc692242b68 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -41,9 +41,6 @@ UBSAN_SANITIZE_kcov.o := n KMSAN_SANITIZE_kcov.o := n CFLAGS_kcov.o := $(call cc-option, -fno-conserve-stack) -fno-stack-protector -# Don't instrument error handlers -CFLAGS_REMOVE_cfi.o := $(CC_FLAGS_CFI) - obj-y += sched/ obj-y += locking/ obj-y += power/ -- cgit v1.2.3