Hello Krzysztof, On 05/17/2016 02:02 AM, Krzysztof Kozlowski wrote: > Although unbinding a pinctrl driver requires root privileges but it > still might be used theoretically in certain attacks (by triggering NULL > pointer exception or memory corruption). > > Samsung pincontrol drivers are essential for system operation so their > removal is not expected. They do not implement remove() driver callback > and they are not buildable as modules. > > Suppression of the unbinding will prevent triggering NULL pointer > exception like this (Odroid XU3): > > $ echo 13400000.pinctrl > /sys/bus/platform/drivers/samsung-pinctrl/unbind > $ cat /sys/kernel/debug/gpio > > Unable to handle kernel NULL pointer dereference at virtual address 00000c44 > pgd = ec41c000 > [00000c44] *pgd=6d448835, *pte=00000000, *ppte=00000000 > Internal error: Oops: 17 [#1] PREEMPT SMP ARM > (samsung_gpio_get) from [<c034f9a0>] (gpiolib_seq_show+0x1b0/0x26c) > (gpiolib_seq_show) from [<c01fb8c0>] (seq_read+0x304/0x4b8) > (seq_read) from [<c02dbc78>] (full_proxy_read+0x4c/0x64) > (full_proxy_read) from [<c01d9fb0>] (__vfs_read+0x2c/0x110) > (__vfs_read) from [<c01db400>] (vfs_read+0x8c/0x110) > (vfs_read) from [<c01db4c4>] (SyS_read+0x40/0x8c) > (SyS_read) from [<c01078c0>] (ret_fast_syscall+0x0/0x3c) > > Suggested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> > --- Reviewed-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx> Best regards, -- Javier Martinez Canillas Open Source Group Samsung Research America -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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