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

[Hans de Goede]

HI,

On 13-11-18 14:21, Jon Hunter wrote:
> On 13/11/2018 10:40, Hans de Goede wrote:
> > 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) ...
> > > >
> > > > [ÂÂ 14.072883] brcmfmac: brcmf_fw_alloc_request: using
> > > > brcm/brcmfmac4329-sdio for chip BCM4329/3
> > > >
> > > > [ÂÂ 14.130287] brcmfmac mmc1:0001:1: Direct firmware load for
> > > > brcm/brcmfmac4329-sdio.nvidia,cardhu-a04.txt failed with error -2
> > > >
> > > > [ÂÂ 14.156283] brcmfmac mmc1:0001:1: Direct firmware load for
> > > > brcm/brcmfmac4329-sdio.txt failed with error -2
> > > >
> > > > [ÂÂ 14.177769] Unable to handle kernel NULL pointer dereference at
> > > > virtual address 00000008
> > > >
> > > > [ÂÂ 14.197303] pgd = 60bfa5f1
> > > >
> > > > [ÂÂ 14.211842] [00000008] *pgd=00000000
> > > >
> > > > [ÂÂ 14.227373] Internal error: Oops: 5 [#1] SMP ARM
> > > >
> > > > [ÂÂ 14.244244] Modules linked in: brcmfmac sha256_generic sha256_arm
> > > > snd cfg80211 brcmutil soundcore snd_soc_tegra30_ahub tegra_wdt
> > > >
> > > > [ÂÂ 14.269109] CPU: 1 PID: 114 Comm: kworker/1:2 Not tainted
> > > > 4.20.0-rc1-next-20181107-gd881de3 #1
> > > >
> > > > [ÂÂ 14.269114] Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
> > > >
> > > > [ÂÂ 14.269154] Workqueue: events request_firmware_work_func
> > > >
> > > > [ÂÂ 14.269177] PC is at efivar_entry_size+0x28/0x90
> > > >
> > > > [ÂÂ 14.269362] LR is at brcmf_fw_complete_request+0x3f8/0x8d4 [brcmfmac]
> > > >
> > > > [ÂÂ 14.269369] pc : [<c0c40718>]ÂÂÂ lr : [<bf2a3ef4>]ÂÂÂ psr: a00d0113
> > > >
> > > > [ÂÂ 14.269374] sp : ede7fe28Â ip : ee983410Â fp : c1787f30
> > > >
> > > > [ÂÂ 14.269378] r10: 00000000Â r9 : 00000000Â r8 : bf2b2258
> > > >
> > > > [ÂÂ 14.269384] r7 : ee983000Â r6 : c1604c48Â r5 : ede7fe88Â r4 :
> > > > edf337c0
> > > >
> > > > [ÂÂ 14.269389] r3 : 00000000Â r2 : 00000000Â r1 : ede7fe88Â 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)
> > > {
> > >  ÂÂÂÂÂ 310:ÂÂÂÂÂÂ e1a05001ÂÂÂÂÂÂÂ movÂÂÂÂ r5, r1
> > >  ÂÂÂÂÂÂÂÂ const struct efivar_operations *ops = __efivars->ops;
> > > ==>Â 314:ÂÂÂÂÂÂ e5936008ÂÂÂÂÂÂÂ ldrÂÂÂÂ 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:
> >
> >  ÂÂÂÂif (!ops)
> >  ÂÂÂÂÂÂÂ return -ENOENT;
> >
> > Which makes it return the same error as when we do have efivar
> > support but the requested variable is not found.
>
> So the above did not work. I see a patch from Arend and I will give this
> a try.

Ah right, looking at Arend's patch my little snippet got the test wrong.

Hopefully Arend's patch will fix things.

Regards,

Hans