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

[Kees Cook]

On Wed, Feb 01, 2023 at 12:11:41AM -0800, John Stultz wrote:
> 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!

Yay for compilers! :)

Was a patch sent to fix this driver?

-- 
Kees Cook