Re: [PATCH 06/17] kthread: cfi: disable callback pointer check with modules
From: Christoph Hellwig <hch@infradead.org>
Date: 2021-03-12 06:13:59
Also in:
bpf, linux-arch, linux-hardening, linux-kbuild, linux-pci, lkml
On Thu, Mar 11, 2021 at 04:49:08PM -0800, Sami Tolvanen wrote:
quoted hunk ↗ jump to hunk
With CONFIG_CFI_CLANG, a callback function passed to __kthread_queue_delayed_work from a module points to a jump table entry defined in the module instead of the one used in the core kernel, which breaks function address equality in this check: WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); Disable the warning when CFI and modules are enabled. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- kernel/kthread.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)diff --git a/kernel/kthread.c b/kernel/kthread.c index 1578973c5740..af5fee350586 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c@@ -963,7 +963,13 @@ static void __kthread_queue_delayed_work(struct kthread_worker *worker, struct timer_list *timer = &dwork->timer; struct kthread_work *work = &dwork->work; - WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); + /* + * With CFI, timer->function can point to a jump table entry in a module,
you keep spewing this comment line that has exactly 81 characters and thus badly messes up read it with a normal termina everywhere. Maybe instead of fixing that in ever duplication hide the whole check in a well documented helper (which would have to be a macro due to the typing involved). _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel