From 4919c073780614df6f996ac33309fbbf2f67b199 Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Thu, 9 Dec 2021 17:34:05 -0800 Subject: [PATCH] clk: Emit a stern warning with writable debugfs enabled commit 489a71964f9d74e697a12cd0ace20ed829eb1f93 upstream. We don't want vendors to be enabling this part of the clk code and shipping it to customers. Exposing the ability to change clk frequencies and parents via debugfs is potentially damaging to the system if folks don't know what they're doing. Emit a strong warning so that the message is clear: don't enable this outside of development systems. Fixes: 37215da5553e ("clk: Add support for setting clk_rate via debugfs") Cc: Geert Uytterhoeven Link: https://lore.kernel.org/r/20211210014237.2130300-1-sboyd@kernel.org Signed-off-by: Stephen Boyd Signed-off-by: Greg Kroah-Hartman --- drivers/clk/clk.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index a277fd4f2f0a6..ac11cefc31911 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -3340,6 +3340,24 @@ static int __init clk_debug_init(void) { struct clk_core *core; +#ifdef CLOCK_ALLOW_WRITE_DEBUGFS + pr_warn("\n"); + pr_warn("********************************************************************\n"); + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n"); + pr_warn("** **\n"); + pr_warn("** WRITEABLE clk DebugFS SUPPORT HAS BEEN ENABLED IN THIS KERNEL **\n"); + pr_warn("** **\n"); + pr_warn("** This means that this kernel is built to expose clk operations **\n"); + pr_warn("** such as parent or rate setting, enabling, disabling, etc. **\n"); + pr_warn("** to userspace, which may compromise security on your system. **\n"); + pr_warn("** **\n"); + pr_warn("** If you see this message and you are not debugging the **\n"); + pr_warn("** kernel, report this immediately to your vendor! **\n"); + pr_warn("** **\n"); + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n"); + pr_warn("********************************************************************\n"); +#endif + rootdir = debugfs_create_dir("clk", NULL); debugfs_create_file("clk_summary", 0444, rootdir, &all_lists, -- 2.30.2