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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: 9fc9e278a5 ("panic: Introduce warn_limit")
Fixes: d4ccd54d28 ("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>
This commit is contained in:
Kees Cook 2022-12-16 12:26:57 -08:00
parent d6a9fb87e9
commit 7535b832c6
2 changed files with 9 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
kernel/exit.c
View File

@ -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

7
kernel/panic.c
View File

@ -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);
}
/**