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author | Krzysztof Kozlowski <k.kozlowski@samsung.com> | 2016-06-16 08:27:35 +0200 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-06-25 13:50:53 -0700 |
commit | e51e4d8a185de90424b03f30181b35f29c46a25a (patch) | |
tree | e4c00a5cc9b8e720e347239cc074e61e2d52674d /drivers/tty | |
parent | 4da22f1418cb6f09e974499794db2f5e59fe8090 (diff) | |
download | lwn-e51e4d8a185de90424b03f30181b35f29c46a25a.tar.gz lwn-e51e4d8a185de90424b03f30181b35f29c46a25a.zip |
serial: samsung: Fix ERR pointer dereference on deferred probe
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: 60e93575476f ("serial: samsung: enable clock before clearing pending interrupts during init")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r-- | drivers/tty/serial/samsung.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c index 99bb23161dd6..f0bd2ec0db59 100644 --- a/drivers/tty/serial/samsung.c +++ b/drivers/tty/serial/samsung.c @@ -1684,7 +1684,7 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport, return -ENODEV; if (port->mapbase != 0) - return 0; + return -EINVAL; /* setup info for port */ port->dev = &platdev->dev; @@ -1738,22 +1738,25 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport, ourport->dma = devm_kzalloc(port->dev, sizeof(*ourport->dma), GFP_KERNEL); - if (!ourport->dma) - return -ENOMEM; + if (!ourport->dma) { + ret = -ENOMEM; + goto err; + } } ourport->clk = clk_get(&platdev->dev, "uart"); if (IS_ERR(ourport->clk)) { pr_err("%s: Controller clock not found\n", dev_name(&platdev->dev)); - return PTR_ERR(ourport->clk); + ret = PTR_ERR(ourport->clk); + goto err; } ret = clk_prepare_enable(ourport->clk); if (ret) { pr_err("uart: clock failed to prepare+enable: %d\n", ret); clk_put(ourport->clk); - return ret; + goto err; } /* Keep all interrupts masked and cleared */ @@ -1769,7 +1772,12 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport, /* reset the fifos (and setup the uart) */ s3c24xx_serial_resetport(port, cfg); + return 0; + +err: + port->mapbase = 0; + return ret; } /* Device driver serial port probe */ |