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[75.72.117.212]) by smtp.gmail.com with ESMTPSA id 8926c6da1cb9f-5b7bd26fdfdsm5209811173.18.2025.11.17.11.13.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Nov 2025 11:13:45 -0800 (PST) Message-ID: Date: Mon, 17 Nov 2025 13:13:44 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] clk: spacemit: fix UBSAN warning during probe To: Charles Mirabile , linux-kernel@vger.kernel.org Cc: spacemit@lists.linux.dev, linux-riscv@lists.infradead.org, linux-clk@vger.kernel.org, mturquette@baylibre.com, sboyd@kernel.org, dlan@gentoo.org, heylenay@4d2.org, troy.mitchell@linux.spacemit.com, inochiama@outlook.com, Yanko Kaneti References: <20251117190329.1337250-1-cmirabil@redhat.com> Content-Language: en-US From: Alex Elder In-Reply-To: <20251117190329.1337250-1-cmirabil@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/17/25 1:03 PM, Charles Mirabile wrote: > When booting with KASAN enabled the following splat is encountered during > probe of the k1 clock driver: > > UBSAN: array-index-out-of-bounds in drivers/clk/spacemit/ccu-k1.c:1044:16 > index 0 is out of range for type 'clk_hw *[*]' > CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.18.0-rc5+ #1 PREEMPT(lazy) > Hardware name: Unknown Unknown Product/Unknown Product, BIOS 2022.10spacemit 10/01/2022 > Call Trace: > [] dump_backtrace+0x28/0x38 > [] show_stack+0x3a/0x50 > [] dump_stack_lvl+0x5a/0x80 > [] dump_stack+0x18/0x20 > [] ubsan_epilogue+0x10/0x48 > [] __ubsan_handle_out_of_bounds+0xa6/0xa8 > [] k1_ccu_probe+0x37e/0x420 > [] platform_probe+0x56/0x98 > [] really_probe+0x9e/0x350 > [] __driver_probe_device+0x80/0x138 > [] driver_probe_device+0x3a/0xd0 > [] __driver_attach+0xac/0x1b8 > [] bus_for_each_dev+0x6c/0xc8 > [] driver_attach+0x26/0x38 > [] bus_add_driver+0x13e/0x268 > [] driver_register+0x52/0x100 > [] __platform_driver_register+0x28/0x38 > [] k1_ccu_driver_init+0x22/0x38 > [] do_one_initcall+0x62/0x2a0 > [] do_initcalls+0x170/0x1a8 > [] kernel_init_freeable+0x16a/0x1e0 > [] kernel_init+0x2c/0x180 > [] ret_from_fork_kernel+0x16/0x1d8 > [] ret_from_fork_kernel_asm+0x16/0x18 > ---[ end trace ]--- > > This is bogus and is simply a result of KASAN consulting the `.num` member > of the struct for bounds information (as it should due to `__counted_by`) > and finding 0 set by kzalloc because it has not been initialized before > the loop that fills in the array. The easy fix is to just move the line > that sets `num` to before the loop that fills the array so that KASAN has > the information it needs to accurately conclude that the access is valid. > > > Fixes: 1b72c59db0add ("clk: spacemit: Add clock support for SpacemiT K1 SoC") > Tested-by: Yanko Kaneti > > Signed-off-by: Charles Mirabile Looks good to me. I haven't used UBSAN but the report is clearly complaining about exactly what you describe. Your fix seems like exactly the right thing to do. Reviewed-by: Alex Elder > --- > drivers/clk/spacemit/ccu-k1.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/clk/spacemit/ccu-k1.c b/drivers/clk/spacemit/ccu-k1.c > index f5a9fe6ba1859..4761bc1e3b6e6 100644 > --- a/drivers/clk/spacemit/ccu-k1.c > +++ b/drivers/clk/spacemit/ccu-k1.c > @@ -1018,6 +1018,8 @@ static int spacemit_ccu_register(struct device *dev, > if (!clk_data) > return -ENOMEM; > > + clk_data->num = data->num; > + > for (i = 0; i < data->num; i++) { > struct clk_hw *hw = data->hws[i]; > struct ccu_common *common; > @@ -1044,8 +1046,6 @@ static int spacemit_ccu_register(struct device *dev, > clk_data->hws[i] = hw; > } > > - clk_data->num = data->num; > - > ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, clk_data); > if (ret) > dev_err(dev, "failed to add clock hardware provider (%d)\n", ret); > > base-commit: 6a23ae0a96a600d1d12557add110e0bb6e32730c