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| author | Kees Cook <keescook@chromium.org> | 2022-12-16 12:26:57 -0800 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2022-12-16 12:26:57 -0800 |
| commit | 7535b832c6399b5ebfc5b53af5c51dd915ee2538 (patch) | |
| tree | eb9699155cf89e65084179522b93106ad2f33faf | |
| parent | d6a9fb87e9d18f3394a9845546bbe868efdccfd2 (diff) | |
| download | linux-7535b832c6399b5ebfc5b53af5c51dd915ee2538.tar.gz linux-7535b832c6399b5ebfc5b53af5c51dd915ee2538.tar.xz | |
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>
| -rw-r--r-- | kernel/exit.c | 6 | ||||
| -rw-r--r-- | 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); } /** |