Commit da937481 authored by Markus Burri's avatar Markus Burri Committed by Jonathan Cameron
Browse files

iio: backend: fix out-of-bound write 



The buffer is set to 80 character. If a caller write more characters,
count is truncated to the max available space in "simple_write_to_buffer".
But afterwards a string terminator is written to the buffer at offset count
without boundary check. The zero termination is written OUT-OF-BOUND.

Add a check that the given buffer is smaller then the buffer to prevent.

Fixes: 035b4989 ("iio: backend: make sure to NULL terminate stack buffer")
Signed-off-by: default avatarMarkus Burri <markus.burri@mt.com>
Reviewed-by: default avatarNuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250508130612.82270-2-markus.burri@mt.com


Cc: <Stable@vger.kernel.org>
Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 19272b37

drivers/iio/industrialio-backend.c

+4 −1
Original line number Diff line number Diff line
@@ -155,11 +155,14 @@ static ssize_t iio_backend_debugfs_write_reg(struct file *file, 
	ssize_t rc;

	int ret;



	if (count >= sizeof(buf))

		return -ENOSPC;



	rc = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, userbuf, count);

	if (rc < 0)

		return rc;



	buf[count] = '\0';

	buf[rc] = '\0';



	ret = sscanf(buf, "%i %i", &back->cached_reg_addr, &val);