• Krzysztof Kozlowski's avatar
    serial: samsung: Fix ERR pointer dereference on deferred probe · e51e4d8a
    Krzysztof Kozlowski authored
    When the clk_get() of "uart" clock returns EPROBE_DEFER, the next re-probe
    finishes with success but uses invalid (ERR_PTR) values.  This leads to
    dereferencing of ERR_PTR stored under ourport->clk:
    
    	12c30000.serial: Controller clock not found
    	(...)
    	12c30000.serial: ttySAC3 at MMIO 0x12c30000 (irq = 61, base_baud = 0) is a S3C6400/10
    	Unable to handle kernel paging request at virtual address fffffdfb
    
    	(clk_prepare) from [<c039f7d0>] (s3c24xx_serial_pm+0x20/0x128)
    	(s3c24xx_serial_pm) from [<c0395414>] (uart_change_pm+0x38/0x40)
    	(uart_change_pm) from [<c039689c>] (uart_add_one_port+0x31c/0x44c)
    	(uart_add_one_port) from [<c03a035c>] (s3c24xx_serial_probe+0x2a8/0x418)
    	(s3c24xx_serial_probe) from [<c03ee110>] (platform_drv_probe+0x50/0xb0)
    	(platform_drv_probe) from [<c03ecb44>] (driver_probe_device+0x1f4/0x2b0)
    	(driver_probe_device) from [<c03eb0c0>] (bus_for_each_drv+0x44/0x8c)
    	(bus_for_each_drv) from [<c03ec8c8>] (__device_attach+0x9c/0x100)
    	(__device_attach) from [<c03ebf54>] (bus_probe_device+0x84/0x8c)
    	(bus_probe_device) from [<c03ec388>] (deferred_probe_work_func+0x60/0x8c)
    	(deferred_probe_work_func) from [<c012fee4>] (process_one_work+0x120/0x328)
    	(process_one_work) from [<c0130150>] (worker_thread+0x2c/0x4ac)
    	(worker_thread) from [<c0135320>] (kthread+0xd8/0xf4)
    	(kthread) from [<c0107978>] (ret_from_fork+0x14/0x3c)
    
    The first unsuccessful clk_get() causes s3c24xx_serial_init_port() to
    exit with failure but the s3c24xx_uart_port is left half-configured
    (e.g. port->mapbase is set, clk contains ERR_PTR).  On next re-probe,
    the function s3c24xx_serial_init_port() will exit early with success
    because of configured port->mapbase and driver will use old values,
    including the ERR_PTR as clock.
    
    Fix this by cleaning the port->mapbase on error path so each re-probe
    will initialize all of the port settings.
    
    Fixes: 60e93575 ("serial: samsung: enable clock before clearing pending interrupts during init")
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarKrzysztof Kozlowski <k.kozlowski@samsung.com>
    Reviewed-by: default avatarJavier Martinez Canillas <javier@osg.samsung.com>
    Tested-by: default avatarJavier Martinez Canillas <javier@osg.samsung.com>
    Tested-by: default avatarKevin Hilman <khilman@baylibre.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    e51e4d8a
samsung.c 62.6 KB