Re: [PATCH 5/6] driver core: Add __alloc_size hint to devm allocators

[John Stultz]

On Tue, Jan 31, 2023 at 11:36 PM Yongqin Liu <yongqin.liu@xxxxxxxxxx> wrote:
>
> Hi, Kees
>
> This change causes "Kernel panic - not syncing: BRK handler: Fatal exception"
> for the android-mainline based hikey960 build, with this commit reverted,
> there is no problem for the build to boot to the homescreen.
> Not sure if you have any idea about it and give some suggestions.
>
> Here is part of the kernel panic log:
>
>     [    9.479878][  T122] ueventd: Loading module
> /vendor/lib/modules/spi-pl022.ko with args ''
>     [    9.480276][  T115] apexd-bootstrap: Pre-allocated loop device 29
>     [    9.480517][  T123] ueventd: LoadWithAliases was unable to load
> of:Nhi3660_i2sT(null)Chisilicon,hi3660-i2s-1.0
>     [    9.480632][  T121] Unexpected kernel BRK exception at EL1
>     [    9.480637][  T121] Internal error: BRK handler:
> 00000000f2000001 [#1] PREEMPT SMP
>     [    9.480644][  T121] Modules linked in: cpufreq_dt(E+)
> hisi_thermal(E+) phy_hi3660_usb3(E) btqca(E) hi6421_pmic_core(E)
> btbcm(E) spi_pl022(E) hi3660_mailbox(E) i2c_designware_platform(E)
> mali_kbase(OE) dw_mmc_k3(E) bluetooth(E) dw_mmc_pltfm(E) dw_mmc(E)
> kirin_drm(E) rfkill(E) kirin_dsi(E) i2c_designware_core(E) k3dma(E)
> drm_dma_helper(E) cma_heap(E) system_heap(E)
>     [    9.480688][  T121] CPU: 4 PID: 121 Comm: ueventd Tainted: G
>        OE      6.2.0-rc6-mainline-14196-g1d9f94ec75b9 #1
>     [    9.480694][  T121] Hardware name: HiKey960 (DT)
>     [    9.480697][  T121] pstate: 20400005 (nzCv daif +PAN -UAO -TCO
> -DIT -SSBS BTYPE=--)
>     [    9.480703][  T121] pc : hi3660_thermal_probe+0x6c/0x74 [hisi_thermal]
>     [    9.480722][  T121] lr : hi3660_thermal_probe+0x38/0x74 [hisi_thermal]
>     [    9.480733][  T121] sp : ffffffc00aa13700
>     [    9.480735][  T121] x29: ffffffc00aa13700 x28: 0000007ff8ae8531
> x27: 00000000000008c0
>     [    9.480743][  T121] x26: ffffffc00aa2a300 x25: ffffffc00aa2ab40
> x24: 000000000000001d
>     [    9.480749][  T121] x23: ffffffc00a29d000 x22: 0000000000000000
> x21: ffffff8001fa4a80
>     [    9.480755][  T121] x20: 0000000000000001 x19: ffffff8001fa4a80
> x18: ffffffc00a8810b0
>     [    9.480761][  T121] x17: 000000007ab542f2 x16: 000000007ab542f2
> x15: ffffffc00aa01000
>     [    9.480767][  T121] x14: ffffffc00966f250 x13: ffffffc0b58f9000
> x12: ffffffc00a055f10
>     [    9.480771][  T123] ueventd: LoadWithAliases was unable to load
> cpu:type:aarch64:feature:,0000,0001,0002,0003,0004,0005,0006,0007,000B
>     [    9.480773][  T121]
>     [    9.480774][  T121] x11: 0000000000000000 x10: 0000000000000001
> x9 : 0000000100000000
>     [    9.480780][  T123] ueventd:
>     [    9.480780][  T121] x8 : ffffffc0044154cb x7 : 0000000000000000
> x6 : 000000000000003f
>     [    9.480786][  T121] x5 : 0000000000000020 x4 : ffffffc0098db323
> x3 : ffffff801aeb62c0
>     [    9.480792][  T121] x2 : ffffff801aeb62c0 x1 : 0000000000000000
> x0 : ffffff8001fa4c80
>     [    9.480798][  T121] Call trace:
>     [    9.480801][  T121]  hi3660_thermal_probe+0x6c/0x74 [hisi_thermal]
>     [    9.480813][  T121]  hisi_thermal_probe+0xbc/0x284 [hisi_thermal]


Taking a look here, it looks pretty obvious:
  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/thermal/hisi_thermal.c#n414

data->nr_sensors = 1;
data->sensor = devm_kzalloc(dev, sizeof(*data->sensor) *
   data->nr_sensors, GFP_KERNEL);

Here as nr_sensors=1, we allocate only one structure for the array.
But then below that, we modify two entries, writing past the valid
array, and corrupting data when writing the second sensor values.

data->sensor[0].id = HI3660_BIG_SENSOR;
data->sensor[0].irq_name = "tsensor_a73";
data->sensor[0].data = data;

data->sensor[1].id = HI3660_LITTLE_SENSOR;
data->sensor[1].irq_name = "tsensor_a53";
data->sensor[1].data = data;

I suspect nr_sensors needs to be set to 2.

Nice work, Kees!

thanks
-john