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gpio: GPIOHANDLE_GET_LINE_VALUES_IOCTL: Fix information leak 

The GPIOHANDLE_GET_LINE_VALUES_IOCTL handler allocates a gpiohandle_data
struct on the stack and then passes it to copy_to_user(). But depending on
the number of requested line handles the struct is only partially
initialized.

This exposes the previous, potentially sensitive, stack content to the
issuing userspace application. To avoid this make sure that the struct is
fully initialized.

Cc: stable@vger.kernel.org
Fixes: d7c51b47ac ("gpio: userspace ABI for reading/writing GPIO lines")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Lars-Peter Clausen 2016-10-18 16:54:02 +02:00 committed by Linus Walleij
parent b8b0e3d303
commit 3eded5d83b
1 changed files with 2 additions and 0 deletions
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2
drivers/gpio/gpiolib.c
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@ -344,6 +344,8 @@ static long linehandle_ioctl(struct file *filep, unsigned int cmd,
if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) {
int val;
memset(&ghd, 0, sizeof(ghd));
/* TODO: check if descriptors are really input */
for (i = 0; i < lh->numdescs; i++) {
val = gpiod_get_value_cansleep(lh->descs[i]);