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 <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>
diff --git a/kernel/panic.c b/kernel/panic.c
index 54deb74..7834c98 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);
}
/**
