[PATCH 05/17] workqueue: cfi: disable callback pointer check with modules
From: Sami Tolvanen <samitolvanen@google.com>
Date: 2021-03-12 00:50:21
Also in:
bpf, linux-arch, linux-hardening, linux-kbuild, linux-pci, lkml
Subsystem:
the rest, workqueue · Maintainers:
Linus Torvalds, Tejun Heo
With CONFIG_CFI_CLANG, a callback function passed to __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 != delayed_work_timer_fn); Disable the warning when CFI and modules are enabled. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- kernel/workqueue.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 0d150da252e8..4db267e5ad2d 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c@@ -1630,7 +1630,14 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, struct work_struct *work = &dwork->work; WARN_ON_ONCE(!wq); - WARN_ON_ONCE(timer->function != delayed_work_timer_fn); + /* + * With CFI, timer->function can point to a jump table entry in a module, + * which fails the comparison. Disable the warning if CFI and modules are + * both enabled. + */ + if (!IS_ENABLED(CONFIG_CFI_CLANG) || !IS_ENABLED(CONFIG_MODULES)) + WARN_ON_ONCE(timer->function != delayed_work_timer_fn); + WARN_ON_ONCE(timer_pending(timer)); WARN_ON_ONCE(!list_empty(&work->entry));
--
2.31.0.rc2.261.g7f71774620-goog
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel