linux-kernel - Re: [REGRESSION] brcmfmac: NULL pointer deference starting next-20181107

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Message-ID: <e68966fe-eb1f-059c-314c-86fdfe455ea6@broadcom.com>
Date:   Tue, 13 Nov 2018 11:33:04 +0100
From:   Arend van Spriel <arend.vanspriel@...adcom.com>
To:     Jon Hunter <jonathanh@...dia.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        linux-wireless@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [REGRESSION] brcmfmac: NULL pointer deference starting
 next-20181107

On 11/13/2018 11:24 AM, Arend van Spriel wrote:
> + Ard as this involves EFI.
>
> On 11/12/2018 2:24 PM, Jon Hunter wrote:
>> Hi Hans, Kalle,
>>
>> Starting with next-20181107 I am seeing the following NULL pointer
>> deference on Tegra (note the firmware is missing on this board) ...
>>
>> [   14.072883] brcmfmac: brcmf_fw_alloc_request: using
>> brcm/brcmfmac4329-sdio for chip BCM4329/3
>>
>> [   14.130287] brcmfmac mmc1:0001:1: Direct firmware load for
>> brcm/brcmfmac4329-sdio.nvidia,cardhu-a04.txt failed with error -2
>>
>> [   14.156283] brcmfmac mmc1:0001:1: Direct firmware load for
>> brcm/brcmfmac4329-sdio.txt failed with error -2
>>
>> [   14.177769] Unable to handle kernel NULL pointer dereference at
>> virtual address 00000008
>>
>> [   14.197303] pgd = 60bfa5f1
>>
>> [   14.211842] [00000008] *pgd=00000000
>>
>> [   14.227373] Internal error: Oops: 5 [#1] SMP ARM
>>
>> [   14.244244] Modules linked in: brcmfmac sha256_generic sha256_arm
>> snd cfg80211 brcmutil soundcore snd_soc_tegra30_ahub tegra_wdt
>>
>> [   14.269109] CPU: 1 PID: 114 Comm: kworker/1:2 Not tainted
>> 4.20.0-rc1-next-20181107-gd881de3 #1
>>
>> [   14.269114] Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
>>
>> [   14.269154] Workqueue: events request_firmware_work_func
>>
>> [   14.269177] PC is at efivar_entry_size+0x28/0x90
>>
>> [   14.269362] LR is at brcmf_fw_complete_request+0x3f8/0x8d4 [brcmfmac]
>>
>> [   14.269369] pc : [<c0c40718>]    lr : [<bf2a3ef4>]    psr: a00d0113
>>
>> [   14.269374] sp : ede7fe28  ip : ee983410  fp : c1787f30
>>
>> [   14.269378] r10: 00000000  r9 : 00000000  r8 : bf2b2258
>>
>> [   14.269384] r7 : ee983000  r6 : c1604c48  r5 : ede7fe88  r4 : edf337c0
>>
>> [   14.269389] r3 : 00000000  r2 : 00000000  r1 : ede7fe88  r0 : c17712c8
>>
>
> Hi Jon,
>
> I tried building drivers/firmware/efi/vars.c using tegra_defconfig. Had
> to enable CONFIG_EFI. So the null pointer access is a 0x00000008 so I
> looked at the disassembly below:
>
> int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
> {
>      310:       e1a05001        mov     r5, r1
>         const struct efivar_operations *ops = __efivars->ops;
> ==>  314:       e5936008        ldr     r6, [r3, #8]
>
> So I think __efivars is NULL on your platform. It is private to the
> source file. Not sure how the driver should deal with this. Maybe use
> efi_enabled() but not sure what feature to use. My best bet would be
> EFI_RUNTIME_SERVICES.

Another API function to check could be efivars_kobject(), which returns 
NULL if __efivars is NULL.

Regards,
Arend