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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Lrlc2IGZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Lrlc2IGZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A4C6CC4CEF5; Wed, 12 Nov 2025 15:51:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762962696; bh=mPwMxgz3xFqEaJ39x4SnmbvTirPUZobKbYy9JCR6z9Y=; h=Date:Subject:To:References:From:In-Reply-To:From; b=Lrlc2IGZmXcABLRyG4Z1Ak2n5LshnHH6DdKCi2hYT3t4x0gN4s/lXRpvQXK9VrW+a C8KEcMOfixTu7L3p3SywEj3PHpV0YyJcL91Vd1okTs2qpy+HNe5lt7sRLLF1hqH50J rQ3m2TOOkjuySQlcnp+F2WnfvH7T660gmCGW1OzPf4Nnx1iafRabqFKrZgWizvX1L3 ACwsJDcE5IzAtbnVQZDjlUji1o5l6HywH3w2fzP433WNiLtS8R9BjxRYLxZ343YdNO 1EHKJn+4+n6PSTxrt9CPeer6h7JEF76M1pTrAaqOXKHnnjdiWjn9T3xYxJflf4lJPb Cf3509FZyrxcw== Message-ID: <589670a9-ac91-4fde-b595-473408b3df18@kernel.org> Date: Wed, 12 Nov 2025 16:51:32 +0100 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] memory: mtk-smi: Fix NULL pointer dereference in config_port To: Jian Hui Lee , Yong Wu , Matthias Brugger , AngeloGioacchino Del Regno , Joerg Roedel , linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20251111124853.2916889-1-jianhui.lee@canonical.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/11/2025 13:48, Jian Hui Lee wrote: > Fix a race condition where mtk_smi_larb_resume() can be called before > mtk_smi_larb_bind() completes, leading to NULL pointer dereference when > accessing larb->mmu and larb->bank. > > Add NULL checks to skip port configuration gracefully when the device > hasn't been bound yet. > > Crash trace: > [ 7.605014] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 > [ 7.605029] Mem abort info: > [ 7.605031] ESR = 0x0000000096000004 > [ 7.605034] EC = 0x25: DABT (current EL), IL = 32 bits > [ 7.605037] SET = 0, FnV = 0 > [ 7.605040] EA = 0, S1PTW = 0 > [ 7.605042] FSC = 0x04: level 0 translation fault > [ 7.605045] Data abort info: > [ 7.605046] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 > [ 7.605049] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 > [ 7.605052] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 > [ 7.605055] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000106755000 > [ 7.605059] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000 > [ 7.605069] Internal error: Oops: 0000000096000004 [#1] SMP > [ 7.605075] Modules linked in: mtk_mdp3(+) snd_compress(+) ac97_bus snd_pcm_dmaengine snd_pcm v4l2_mem2mem videobufo > [ 7.605223] pwm_mtk_disp spmi_mtk_pmif spmi_devres clk_mt8188_imp_iic_wrap spi_mt65xx mmc_hsq stmmac clk_mt8188_ado > [ 7.605267] CPU: 5 UID: 0 PID: 417 Comm: (udev-worker) Not tainted 6.17.2-custom #29 PREEMPT(voluntary) > [ 7.605273] Hardware name: mediatek Genio 700 EVK P1V4 (eMMC Boot)/Genio 700 EVK P1V4, BIOS 2022.10-gb56d2a20f5 10/2 > [ 7.605278] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 7.605283] pc : mtk_smi_larb_config_port_gen2_general+0x2a8/0x458 [mtk_smi] > [ 7.605301] lr : mtk_smi_larb_config_port_gen2_general+0x110/0x458 [mtk_smi] > [ 7.605307] sp : ffff8000867f3370 > [ 7.605309] x29: ffff8000867f33e0 x28: 0000000000000000 x27: ffff80007c403fcc > [ 7.605317] x26: 000000000000000a x25: ffff0000d5107c80 x24: ffff80007c4040f8 > [ 7.605325] x23: ffff80007c4040f8 x22: ffff80007c403fcc x21: ffff80007c43c918 > [ 7.605332] x20: 0000000000000007 x19: ffff80008685d218 x18: ffff8000863b90e8 > [ 7.605340] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 > [ 7.605346] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 > [ 7.605353] x11: 0000000000000000 x10: 0000000000000000 x9 : ffff80007c403fcc > [ 7.605360] x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000 > [ 7.605367] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000 > [ 7.605373] x2 : 0000000000000000 x1 : ffff8000867f33b8 x0 : 0000000000000000 > [ 7.605381] Call trace: > [ 7.605384] mtk_smi_larb_config_port_gen2_general+0x2a8/0x458 [mtk_smi] (P) > [ 7.605393] mtk_smi_larb_resume+0xbc/0x130 [mtk_smi] > [ 7.605399] pm_generic_runtime_resume+0x38/0x80 > [ 7.605410] __genpd_runtime_resume+0x3c/0xb8 > [ 7.605419] genpd_runtime_resume+0xec/0x338 > [ 7.605425] __rpm_callback+0x54/0x210 > [ 7.605431] rpm_callback+0x94/0xa8 > [ 7.605436] rpm_resume+0x484/0x668 > [ 7.605442] __pm_runtime_resume+0x68/0xd8 > [ 7.605447] pm_runtime_get_suppliers+0x6c/0xb8 > [ 7.605453] __driver_probe_device+0x5c/0x1c8 > [ 7.605461] driver_probe_device+0x48/0x188 > [ 7.605466] __driver_attach+0x14c/0x2c8 > [ 7.605471] bus_for_each_dev+0x88/0x110 > [ 7.605476] driver_attach+0x30/0x60 > [ 7.605481] bus_add_driver+0x17c/0x2e8 > [ 7.605486] driver_register+0x68/0x178 > [ 7.605492] __platform_driver_register+0x30/0x60 > [ 7.605498] mdp_driver_init+0x2c/0xff8 [mtk_mdp3] > [ 7.605519] do_one_initcall+0x64/0x378 > [ 7.605526] do_init_module+0xa4/0x2e0 > [ 7.605534] load_module+0x24a8/0x2618 > [ 7.605541] init_module_from_file+0x98/0x118 > [ 7.605547] __arm64_sys_finit_module+0x284/0x380 > [ 7.605554] invoke_syscall+0x74/0x128 > [ 7.605560] el0_svc_common.constprop.0+0x114/0x140 > [ 7.605565] do_el0_svc+0x28/0x58 > [ 7.605570] el0_svc+0x44/0x1f0 > [ 7.605579] el0t_64_sync_handler+0xc0/0x108 > [ 7.605586] el0t_64_sync+0x1b8/0x1c0 > [ 7.605594] Code: d2800011 d65f03c0 b9808b22 910123e1 (b9400003) > [ 7.605599] ---[ end trace 0000000000000000 ]--- Please trim the traces from all irrelevant information. > > Fixes: e6dec92308628 ("iommu/mediatek: Add mt2712 IOMMU support") Add Cc stable. > Signed-off-by: Jian Hui Lee > --- > drivers/memory/mtk-smi.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/memory/mtk-smi.c b/drivers/memory/mtk-smi.c > index 733e22f695ab..8eb043ff8280 100644 > --- a/drivers/memory/mtk-smi.c > +++ b/drivers/memory/mtk-smi.c > @@ -244,6 +244,10 @@ static int mtk_smi_larb_config_port_gen2_general(struct device *dev) > struct arm_smccc_res res; > int i; > > + /* larb->mmu and larb->bank are set in bind(), may not be ready yet */ And how do you synchronize this between CPUs? IOW, what certainty you have that this CPU sees correct data and the checks below have any sense? > + if (!larb->mmu || !larb->bank) > + return 0; > + > if (BIT(larb->larbid) & larb->larb_gen->larb_direct_to_common_mask) > return 0; > Best regards, Krzysztof