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Subject: Re: [PATCH net-next] net: stmmac: Fix kernel panic due to NULL
 pointer dereference of fpe_cfg
To:     mohammad.athari.ismail@intel.com,
        Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Russell King <linux@armlinux.org.uk>
Cc:     Ong Boon Leong <boon.leong.ong@intel.com>,
        Voon Weifeng <weifeng.voon@intel.com>, vee.khee.wong@intel.com,
        Tan Tee Min <tee.min.tan@intel.com>, netdev@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
From:   Marek Szyprowski <m.szyprowski@samsung.com>
Message-ID: <31b97d50-d187-c3a8-59bf-140d8c7990e5@samsung.com>
Date:   Fri, 26 Mar 2021 11:55:14 +0100
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References: <CGME20210326091110eucas1p1626ecb9b89c282bdbc6fe9b6ed966932@eucas1p1.samsung.com>
        <20210326091046.26391-1-mohammad.athari.ismail@intel.com>
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On 26.03.2021 10:10, mohammad.athari.ismail@intel.com wrote:
> From: Mohammad Athari Bin Ismail <mohammad.athari.ismail@intel.com>
>
> In this patch, "net: stmmac: support FPE link partner hand-shaking
> procedure", priv->plat->fpe_cfg wouldn`t be "devm_kzalloc"ed if
> dma_cap->frpsel is 0 (Flexible Rx Parser is not supported in SoC) in
> tc_init(). So, fpe_cfg will be remain as NULL and accessing it will cause
> kernel panic.
>
> To fix this, move the "devm_kzalloc"ing of priv->plat->fpe_cfg before
> dma_cap->frpsel checking in tc_init(). Additionally, checking of
> priv->dma_cap.fpesel is added before calling stmmac_fpe_link_state_handle()
> as only FPE supported SoC is allowed to call the function.
>
> Below is the kernel panic dump reported by Marek Szyprowski
> <m.szyprowski@samsung.com>:
>
> meson8b-dwmac ff3f0000.ethernet eth0: PHY [0.0:00] driver [RTL8211F Gigabit Ethernet] (irq=35)
> meson8b-dwmac ff3f0000.ethernet eth0: No Safety Features support found
> meson8b-dwmac ff3f0000.ethernet eth0: PTP not supported by HW
> meson8b-dwmac ff3f0000.ethernet eth0: configuring for phy/rgmii link mode
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000001
> Mem abort info:
> ...
> user pgtable: 4k pages, 48-bit VAs, pgdp=00000000044eb000
> [0000000000000001] pgd=0000000000000000, p4d=0000000000000000
> Internal error: Oops: 96000004 [#1] PREEMPT SMP
> Modules linked in: dw_hdmi_i2s_audio dw_hdmi_cec meson_gxl realtek meson_gxbb_wdt snd_soc_meson_axg_sound_card dwmac_generic axg_audio meson_dw_hdmi crct10dif_ce snd_soc_meson_card_utils snd_soc_meson_axg_tdmout panfrost rc_odroid gpu_sched reset_meson_audio_arb meson_ir snd_soc_meson_g12a_tohdmitx snd_soc_meson_axg_frddr sclk_div clk_phase snd_soc_meson_codec_glue dwmac_meson8b snd_soc_meson_axg_fifo stmmac_platform meson_rng meson_drm stmmac rtc_meson_vrtc rng_core meson_canvas pwm_meson dw_hdmi mdio_mux_meson_g12a pcs_xpcs snd_soc_meson_axg_tdm_interface snd_soc_meson_axg_tdm_formatter nvmem_meson_efuse display_connector
> CPU: 1 PID: 7 Comm: kworker/u8:0 Not tainted 5.12.0-rc4-next-20210325+
> Hardware name: Hardkernel ODROID-C4 (DT)
> Workqueue: events_power_efficient phylink_resolve
> pstate: 20400009 (nzCv daif +PAN -UAO -TCO BTYPE=--)
> pc : stmmac_mac_link_up+0x14c/0x348 [stmmac]
> lr : stmmac_mac_link_up+0x284/0x348 [stmmac] ...
> Call trace:
>   stmmac_mac_link_up+0x14c/0x348 [stmmac]
>   phylink_resolve+0x104/0x420
>   process_one_work+0x2a8/0x718
>   worker_thread+0x48/0x460
>   kthread+0x134/0x160
>   ret_from_fork+0x10/0x18
> Code: b971ba60 350007c0 f958c260 f9402000 (39400401)
> ---[ end trace 0c9deb6c510228aa ]---
>
> Fixes: 5a5586112b92 ("net: stmmac: support FPE link partner hand-shaking
> procedure")
> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Signed-off-by: Mohammad Athari Bin Ismail <mohammad.athari.ismail@intel.com>

This fixes my issue. Thanks!

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---
>   .../net/ethernet/stmicro/stmmac/stmmac_main.c |  6 ++++--
>   .../net/ethernet/stmicro/stmmac/stmmac_tc.c   | 20 +++++++++----------
>   2 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 170296820af0..27faf5e49360 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -997,7 +997,8 @@ static void stmmac_mac_link_down(struct phylink_config *config,
>   	stmmac_eee_init(priv);
>   	stmmac_set_eee_pls(priv, priv->hw, false);
>   
> -	stmmac_fpe_link_state_handle(priv, false);
> +	if (priv->dma_cap.fpesel)
> +		stmmac_fpe_link_state_handle(priv, false);
>   }
>   
>   static void stmmac_mac_link_up(struct phylink_config *config,
> @@ -1097,7 +1098,8 @@ static void stmmac_mac_link_up(struct phylink_config *config,
>   		stmmac_set_eee_pls(priv, priv->hw, true);
>   	}
>   
> -	stmmac_fpe_link_state_handle(priv, true);
> +	if (priv->dma_cap.fpesel)
> +		stmmac_fpe_link_state_handle(priv, true);
>   }
>   
>   static const struct phylink_mac_ops stmmac_phylink_mac_ops = {
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> index 1d84ee359808..4e70efc45458 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
> @@ -254,6 +254,16 @@ static int tc_init(struct stmmac_priv *priv)
>   			 priv->flow_entries_max);
>   	}
>   
> +	if (!priv->plat->fpe_cfg) {
> +		priv->plat->fpe_cfg = devm_kzalloc(priv->device,
> +						   sizeof(*priv->plat->fpe_cfg),
> +						   GFP_KERNEL);
> +		if (!priv->plat->fpe_cfg)
> +			return -ENOMEM;
> +	} else {
> +		memset(priv->plat->fpe_cfg, 0, sizeof(*priv->plat->fpe_cfg));
> +	}
> +
>   	/* Fail silently as we can still use remaining features, e.g. CBS */
>   	if (!dma_cap->frpsel)
>   		return 0;
> @@ -298,16 +308,6 @@ static int tc_init(struct stmmac_priv *priv)
>   	dev_info(priv->device, "Enabling HW TC (entries=%d, max_off=%d)\n",
>   			priv->tc_entries_max, priv->tc_off_max);
>   
> -	if (!priv->plat->fpe_cfg) {
> -		priv->plat->fpe_cfg = devm_kzalloc(priv->device,
> -						   sizeof(*priv->plat->fpe_cfg),
> -						   GFP_KERNEL);
> -		if (!priv->plat->fpe_cfg)
> -			return -ENOMEM;
> -	} else {
> -		memset(priv->plat->fpe_cfg, 0, sizeof(*priv->plat->fpe_cfg));
> -	}
> -
>   	return 0;
>   }
>   

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland