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

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Date:   Tue, 13 Nov 2018 11:40:08 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Arend van Spriel <arend.vanspriel@...adcom.com>,
        Jon Hunter <jonathanh@...dia.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

Hi,

On 13-11-18 11:24, 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.

Ah right, thank you for catching this I had looking into this
on my TODO list, but you beat me to it.

IMHO the best fix here would be to modify efivar_entry_size(),
adding:

	if (!ops)
		return -ENOENT;

Which makes it return the same error as when we do have efivar
support but the requested variable is not found.

Regards,

Hans





> 
>          efi_status_t status;
> 
>          *size = 0;
>       318:       e3a03000        mov     r3, #0
>       31c:       e5813000        str     r3, [r1]
> 
>          if (down_interruptible(&efivars_lock))
>       320:       ebfffffe        bl      0 <down_interruptible>
>       324:       e2504000        subs    r4, r0, #0
>       328:       1a000012        bne     378 <efivar_entry_size+0x80>
>                  return -EINTR;
>          status = ops->get_variable(entry->var.VariableName,
> 
> Regards,
> Arend
> 
>> [   14.269398] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
>>
>> [   14.269404] Control: 10c5387d  Table: ad16804a  DAC: 00000051
>>
>> [   14.269417] Process kworker/1:2 (pid: 114, stack limit = 0x984bfbff)
>>
>> [   14.269423] Stack: (0xede7fe28 to 0xede80000)
>>
>> [   14.269434] fe20:                   00000000 c1604c48 edf336e0 edf337c0 ee983000 c1604c48
>>
>> [   14.269447] fe40: edf336e0 bf2a3ef4 edf339db c0466bcc edf339c0 edd1417c edd14008 00000000
>>
>> [   14.269460] fe60: 006000c0 edf33b40 edf339c0 edf33250 c0f9110c edf33b40 c17db2d0 edf339c0
>>
>> [   14.269471] fe80: 00000000 edd14008 00000000 0076006e 00610072 0000006d edf33940 00000003
>>
>> [   14.269482] fea0: edf33980 c0923f84 edf33840 edf33940 edf33980 ede7ff1c c0f9110c c0924410
>>
>> [   14.269492] fec0: 7fffffff d9025ae9 00000001 edf337c0 00000000 ef7b9e00 edf33804 ef7bd000
>>
>> [   14.269512] fee0: 00000000 00000000 c1787f30 bf2a4438 ee952280 00000000 edf33800 ee952280
>>
>> [   14.678917] ff00: ef7b9e00 edf33804 ef7bd000 c0924738 00000000 00000003 00000001 edf33940
>>
>> [   14.678931] ff20: edf33800 c035ee0c ef7b9e00 ef7b9e18 ede7e018 ee952280 ef7b9e00 ef7b9e18
>>
>> [   14.720757] ff40: ede7e018 c17878b8 ee952294 c1603d00 00000008 c035f130 eea99d9c ede7e000
>>
>> [   14.720769] ff60: ee970740 c1603d00 eea99d9c eea99d80 ee970740 00000000 eea99d9c ee952280
>>
>> [   14.720785] ff80: c035f0f0 ee911ebc 00000000 c0364418 ee970740 c03642f0 00000000 00000000
>>
>> [   14.783682] ffa0: 00000000 00000000 00000000 c03010e8 00000000 00000000 00000000 00000000
>>
>> [   14.783693] ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
>>
>> [   14.783707] ffe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
>>
>> [   14.846132] [<c0c40718>] (efivar_entry_size) from [<bf2a3ef4>] (brcmf_fw_complete_request+0x3f8/0x8d4 [brcmfmac])
>>
>> [   14.846253] [<bf2a3ef4>] (brcmf_fw_complete_request [brcmfmac]) from [<bf2a4438>] (brcmf_fw_request_done+0x68/0x11c [brcmfmac])
>>
>> [   14.893363] [<bf2a4438>] (brcmf_fw_request_done [brcmfmac]) from [<c0924738>] (request_firmware_work_func+0x40/0x68)
>>
>> [   14.893396] [<c0924738>] (request_firmware_work_func) from [<c035ee0c>] (process_one_work+0x164/0x448)
>>
>> [   14.939206] [<c035ee0c>] (process_one_work) from [<c035f130>] (worker_thread+0x40/0x524)
>>
>> [   14.939228] [<c035f130>] (worker_thread) from [<c0364418>] (kthread+0x128/0x158)
>>
>> [   14.981096] [<c0364418>] (kthread) from [<c03010e8>] (ret_from_fork+0x14/0x2c)
>>
>> [   14.981102] Exception stack(0xede7ffb0 to 0xede7fff8)
>>
>> [   14.981112] ffa0:                                     00000000 00000000 00000000 00000000
>>
>> [   15.041390] ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
>>
>> [   15.041399] ffe0: 00000000 00000000 00000000 00000000 00000013 00000000
>>
>> [   15.041415] Code: e1a07000 e30102c8 e34c0177 e1a05001 (e5926008)
>>
>> [   15.041491] ---[ end trace 06697c36d390de92 ]---
>>
>