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gpio: virtuser: Fix uninitialized data bug in gpio_virtuser_direction_do_write()

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If *ppos is non-zero (user-space write split over multiple calls to
write()) then simple_write_to_buffer() won't initialize the start of the
buffer. Really, non-zero values for *ppos aren't going to work at all.
Check for that and return -EINVAL at the start of the function.

Fixes: 91581c4b3f ("gpio: virtuser: new virtual testing driver for the GPIO API")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Link: https://patch.msgid.link/ahP3BJWWy-m_qI0X@stanley.mountain
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
This commit is contained in:
Dan Carpenter 2026-05-25 10:15:16 +03:00 committed by Bartosz Golaszewski
parent 9d7697fabb
commit 8a122b5e72
1 changed files with 2 additions and 2 deletions
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4
drivers/gpio/gpio-virtuser.c
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@ -397,7 +397,7 @@ static ssize_t gpio_virtuser_direction_do_write(struct file *file,
char buf[32], *trimmed;
int ret, dir, val = 0;
if (count >= sizeof(buf))
if (*ppos != 0 || count >= sizeof(buf))
return -EINVAL;
ret = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, user_buf, count);
@ -622,7 +622,7 @@ static ssize_t gpio_virtuser_consumer_write(struct file *file,
char buf[GPIO_VIRTUSER_NAME_BUF_LEN + 2];
int ret;
if (count >= sizeof(buf))
if (*ppos != 0 || count >= sizeof(buf))
return -EINVAL;
ret = simple_write_to_buffer(buf, GPIO_VIRTUSER_NAME_BUF_LEN, ppos,