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authorKees Cook <keescook@chromium.org>2022-12-16 12:26:57 -0800
committerKees Cook <keescook@chromium.org>2022-12-16 12:26:57 -0800
commit7535b832c6399b5ebfc5b53af5c51dd915ee2538 (patch)
treeeb9699155cf89e65084179522b93106ad2f33faf /kernel/exit.c
parentd6a9fb87e9d18f3394a9845546bbe868efdccfd2 (diff)
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>
Diffstat (limited to 'kernel/exit.c')
-rw-r--r--kernel/exit.c6
1 files changed, 4 insertions, 2 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