wifi: iwlwifi: pcie: Fix integer overflow in iwl_write_to_user_buf

In the Linux kernel, the following vulnerability has been resolved:

wifi: iwlwifi: pcie: Fix integer overflow in iwl_write_to_user_buf

An integer overflow occurs in the iwl_write_to_user_buf() function,

which is called by the iwl_dbgfs_monitor_data_read() function.

static bool iwl_write_to_user_buf(char __user *user_buf, ssize_t count,

void *buf, ssize_t *size,

ssize_t *bytes_copied)

{

int buf_size_left = count - *bytes_copied;

buf_size_left = buf_size_left - (buf_size_left % sizeof(u32));

if (*size > buf_size_left)

*size = buf_size_left;

If the user passes a SIZE_MAX value to the "ssize_t count" parameter,

the ssize_t count parameter is assigned to "int buf_size_left".

Then compare "*size" with "buf_size_left" . Here, "buf_size_left" is a

negative number, so "*size" is assigned "buf_size_left" and goes into

the third argument of the copy_to_user function, causing a heap overflow.

This is not a security vulnerability because iwl_dbgfs_monitor_data_read()

is a debugfs operation with 0400 privileges.