Messages in this thread Patch in this message | | | From | Kees Cook <> | Subject | [PATCH] exit: Use READ_ONCE() for all oops/warn limit reads | Date | Fri, 16 Dec 2022 12:30:28 -0800 |
| |
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 <peterz@infradead.org> 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" <ebiederm@xmission.com> Cc: Jann Horn <jannh@google.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Petr Mladek <pmladek@suse.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Marco Elver <elver@google.com> Cc: tangmeng <tangmeng@uniontech.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Kees Cook <keescook@chromium.org> --- kernel/exit.c | 6 ++++-- kernel/panic.c | 7 +++++-- 2 files changed, 9 insertions(+), 4 deletions(-)
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); } /** -- 2.34.1
| |