Re: [PATCH v2 2/2] clk: samsung: exynos5: Fix kfree() of const memory on setting driver_override

Geert Uytterhoeven
2019-02-21T15:44:37Z

On Thu, Feb 21, 2019 at 12:46 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> Platform driver driver_override field should not be initialized from
> const memory because the core later kfree() it. If driver_override is
> manually set later through sysfs, kfree() of old value leads to:
>
> $ echo "new_value" > /sys/bus/platform/drivers/.../driver_override
>
> kernel BUG at ../mm/slub.c:3960!
> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
> ...
> (kfree) from [<c058e8c0>] (platform_set_driver_override+0x84/0xac)
> (platform_set_driver_override) from [<c058e908>] (driver_override_store+0x20/0x34)
> (driver_override_store) from [<c031f778>] (kernfs_fop_write+0x100/0x1dc)
> (kernfs_fop_write) from [<c0296de8>] (__vfs_write+0x2c/0x17c)
> (__vfs_write) from [<c02970c4>] (vfs_write+0xa4/0x188)
> (vfs_write) from [<c02972e8>] (ksys_write+0x4c/0xac)
> (ksys_write) from [<c0101000>] (ret_fast_syscall+0x0/0x28)
>
> The clk-exynos5-subcmu driver uses override only for the purpose of
> creating meaningful names for children devices (matching names of power
> domains, e.g. DISP, MFC). The driver_override was not developed for
> this purpose so just switch to default names of devices to fix the
> issue.
>
> Fixes: b06a532bf1fa ("clk: samsung: Add Exynos5 sub-CMU clock driver")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

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