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SubjectRe: [PATCH v2 4/4] thermal/of: Fix free after use in thermal_of_unregister()
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On 8/9/22 01:56, Daniel Lezcano wrote:
> The thermal zone is freed after being unregistered. The release method
> devm_thermal_zone_device_register() calls
> -> thermal_of_zone_device_unregister()
>
> This one calls thermal_zone_device_unregister() which frees the
> thermal zone. However, thermal_of_zone_device_unregister() does access
> this freed pointer to free different resources allocated by the
> thermal_of framework which is invalid.
>
> It results in a kernel panic:
>
> [ 1.915140] thermal_sys: Failed to find thermal zone for tmu id=2
> [ 1.921279] qoriq_thermal 1f80000.tmu: Failed to register sensors
> [ 1.927395] qoriq_thermal: probe of 1f80000.tmu failed with error -22
> [ 1.934189] Unable to handle kernel paging request at virtual address 01adadadadadad88
> [ 1.942146] Mem abort info:
> [ 1.944948] ESR = 0x0000000096000004
> [ 1.948708] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 1.954042] SET = 0, FnV = 0
> [ 1.957107] EA = 0, S1PTW = 0
> [ 1.960253] FSC = 0x04: level 0 translation fault
> [ 1.965147] Data abort info:
> [ 1.968030] ISV = 0, ISS = 0x00000004
> [ 1.971878] CM = 0, WnR = 0
> [ 1.974852] [01adadadadadad88] address between user and kernel address ranges
> [ 1.982016] Internal error: Oops: 96000004 [#1] SMP
> [ 1.986907] Modules linked in:
> [ 1.989969] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.19.0-next-20220808-00080-g1c46f44502e0 #1697
> [ 1.999135] Hardware name: Kontron KBox A-230-LS (DT)
> [ 2.004199] pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 2.011185] pc : kfree+0x5c/0x3c0
> [ 2.014516] lr : devm_thermal_of_zone_release+0x38/0x60
> [ 2.019761] sp : ffff80000a22bad0
> [ 2.023081] x29: ffff80000a22bad0 x28: 0000000000000000 x27: ffff800009960464
> [ 2.030245] x26: ffff800009a16960 x25: 0000000000000006 x24: ffff800009f09a40
> [ 2.037407] x23: ffff800009ab9008 x22: ffff800008d0eea8 x21: 01adadadadadad80
> [ 2.044569] x20: 6b6b6b6b6b6b6b6b x19: ffff00200232b800 x18: 00000000fffffffb
> [ 2.051731] x17: ffff800008d0eea0 x16: ffff800008d07d44 x15: ffff800008d0d154
> [ 2.056647] usb 1-1: new high-speed USB device number 2 using xhci-hcd
> [ 2.058893] x14: ffff800008d0cddc x13: ffff8000088d1c2c x12: ffff8000088d5034
> [ 2.072597] x11: ffff8000088d46d4 x10: 0000000000000000 x9 : ffff800008d0eea8
> [ 2.079759] x8 : ffff002000b1a158 x7 : bbbbbbbbbbbbbbbb x6 : ffff80000a0f53b8
> [ 2.086921] x5 : ffff80000a22b960 x4 : 0000000000000000 x3 : 0000000000000000
> [ 2.094082] x2 : fffffc0000000000 x1 : ffff002000838040 x0 : 01adb1adadadad80
> [ 2.101244] Call trace:
> [ 2.103692] kfree+0x5c/0x3c0
> [ 2.106666] devm_thermal_of_zone_release+0x38/0x60
> [ 2.111561] release_nodes+0x64/0xd0
> [ 2.115146] devres_release_all+0xbc/0x350
> [ 2.119253] device_unbind_cleanup+0x20/0x70
> [ 2.123536] really_probe+0x1a0/0x2e4
> [ 2.127208] __driver_probe_device+0x80/0xec
> [ 2.131490] driver_probe_device+0x44/0x130
> [ 2.135685] __driver_attach+0x104/0x1b4
> [ 2.139619] bus_for_each_dev+0x7c/0xe0
> [ 2.143465] driver_attach+0x30/0x40
> [ 2.147048] bus_add_driver+0x160/0x210
> [ 2.150894] driver_register+0x84/0x140
> [ 2.154741] __platform_driver_register+0x34/0x40
> [ 2.159461] qoriq_tmu_init+0x28/0x34
> [ 2.163133] do_one_initcall+0x50/0x250
> [ 2.166979] kernel_init_freeable+0x278/0x31c
> [ 2.171349] kernel_init+0x30/0x140
> [ 2.174847] ret_from_fork+0x10/0x20
> [ 2.178433] Code: b25657e2 d34cfc00 d37ae400 8b020015 (f94006a1)
> [ 2.184546] ---[ end trace 0000000000000000 ]---
>
> Store the allocated resource pointers before the thermal zone is free
> and use them to release the resource after unregistering the thermal
> zone.
>
> Reported-by: Michael Walle <michael@walle.cc>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> Tested-by: Michael Walle <michael@walle.cc>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> drivers/thermal/thermal_of.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/thermal_of.c b/drivers/thermal/thermal_of.c
> index 3effc729be4b..fd2fb84bf246 100644
> --- a/drivers/thermal/thermal_of.c
> +++ b/drivers/thermal/thermal_of.c
> @@ -596,11 +596,15 @@ static int thermal_of_unbind(struct thermal_zone_device *tz,
> */
> void thermal_of_zone_unregister(struct thermal_zone_device *tz)
> {
> + struct thermal_trip *trips = tz->trips;
> + struct thermal_zone_params *tzp = tz->tzp;
> + struct thermal_zone_device_ops *ops = tz->ops;
> +
> thermal_zone_device_disable(tz);
> thermal_zone_device_unregister(tz);
> - kfree(tz->trips);
> - kfree(tz->tzp);
> - kfree(tz->ops);
> + kfree(trips);
> + kfree(tzp);
> + kfree(ops);
> }
> EXPORT_SYMBOL_GPL(thermal_of_zone_unregister);
>

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