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| author | David Brownell <dbrownell@users.sourceforge.net> | 2008-10-20 20:50:10 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-11-10 22:17:51 +0300 |
| commit | fa1b284673e834fb814fb0a638d4259e619ac1ec (patch) | |
| tree | 290f66359d22e228d77261491ea1479c63e20f62 | |
| parent | a9dc6714276111b43349ee81db71dda9b31c8c28 (diff) | |
| download | linux-fa1b284673e834fb814fb0a638d4259e619ac1ec.tar.xz | |
gpiolib: fix oops in gpio_get_value_cansleep()
commit 978ccaa8ea5d8c7bf6b676209f2fc126eae6355b upstream
We can get the following oops from gpio_get_value_cansleep() when a GPIO
controller doesn't provide a get() callback:
Unable to handle kernel paging request for instruction fetch
Faulting instruction address: 0x00000000
Oops: Kernel access of bad area, sig: 11 [#1]
[...]
NIP [00000000] 0x0
LR [c0182fb0] gpio_get_value_cansleep+0x40/0x50
Call Trace:
[c7b79e80] [c0183f28] gpio_value_show+0x5c/0x94
[c7b79ea0] [c01a584c] dev_attr_show+0x30/0x7c
[c7b79eb0] [c00d6b48] fill_read_buffer+0x68/0xe0
[c7b79ed0] [c00d6c54] sysfs_read_file+0x94/0xbc
[c7b79ef0] [c008f24c] vfs_read+0xb4/0x16c
[c7b79f10] [c008f580] sys_read+0x4c/0x90
[c7b79f40] [c0013a14] ret_from_syscall+0x0/0x38
It's OK to request the value of *any* GPIO; most GPIOs are bidirectional,
so configuring them as outputs just enables an output driver and doesn't
disable the input logic.
So the problem is that gpio_get_value_cansleep() isn't making the same
sanity check that gpio_get_value() does: making sure this GPIO isn't one
of the atypical "no input logic" cases.
Reported-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/gpio/gpiolib.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index beaf6b3a37dc..2e85d82472fe 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -517,7 +517,7 @@ int gpio_get_value_cansleep(unsigned gpio) might_sleep_if(extra_checks); chip = gpio_to_chip(gpio); - return chip->get(chip, gpio - chip->base); + return chip->get ? chip->get(chip, gpio - chip->base) : 0; } EXPORT_SYMBOL_GPL(gpio_get_value_cansleep); |