| Message ID | 20220904193115.GA28134@ubuntu |
|---|---|
| State | Accepted |
| Commit | cacdb14b1c8d3804a3a7d31773bc7569837b71a4 |
| Headers | show |
| Series | [v2] HID: roccat: Fix Use-After-Free in roccat_read | expand |
On Sun, 4 Sep 2022, Hyunwoo Kim wrote: > roccat_report_event() is responsible for registering > roccat-related reports in struct roccat_device. [ ... snip ... ] > Since the device node of this driver does not set separate permissions, > this is not a security vulnerability, but because it is used for > requesting screen display of profile or dpi settings, > a user using the roccat device can apply udev to this device node or > There is a possibility to use it by giving. > > Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com> Applied, thanks.
diff --git a/drivers/hid/hid-roccat.c b/drivers/hid/hid-roccat.c index 26373b82fe81..6da80e442fdd 100644 --- a/drivers/hid/hid-roccat.c +++ b/drivers/hid/hid-roccat.c @@ -257,6 +257,8 @@ int roccat_report_event(int minor, u8 const *data) if (!new_value) return -ENOMEM; + mutex_lock(&device->cbuf_lock); + report = &device->cbuf[device->cbuf_end]; /* passing NULL is safe */ @@ -276,6 +278,8 @@ int roccat_report_event(int minor, u8 const *data) reader->cbuf_start = (reader->cbuf_start + 1) % ROCCAT_CBUF_SIZE; } + mutex_unlock(&device->cbuf_lock); + wake_up_interruptible(&device->wait); return 0; }
roccat_report_event() is responsible for registering roccat-related reports in struct roccat_device. int roccat_report_event(int minor, u8 const *data) { struct roccat_device *device; struct roccat_reader *reader; struct roccat_report *report; uint8_t *new_value; device = devices[minor]; new_value = kmemdup(data, device->report_size, GFP_ATOMIC); if (!new_value) return -ENOMEM; report = &device->cbuf[device->cbuf_end]; /* passing NULL is safe */ kfree(report->value); ... The registered report is stored in the struct roccat_device member "struct roccat_report cbuf[ROCCAT_CBUF_SIZE];". If more reports are received than the "ROCCAT_CBUF_SIZE" value, kfree() the saved report from cbuf[0] and allocates a new reprot. Since there is no lock when this kfree() is performed, kfree() can be performed even while reading the saved report. static ssize_t roccat_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos) { struct roccat_reader *reader = file->private_data; struct roccat_device *device = reader->device; struct roccat_report *report; ssize_t retval = 0, len; DECLARE_WAITQUEUE(wait, current); mutex_lock(&device->cbuf_lock); ... report = &device->cbuf[reader->cbuf_start]; /* * If report is larger than requested amount of data, rest of report * is lost! */ len = device->report_size > count ? count : device->report_size; if (copy_to_user(buffer, report->value, len)) { retval = -EFAULT; goto exit_unlock; } ... The roccat_read() function receives the device->cbuf report and delivers it to the user through copy_to_user(). If the N+ROCCAT_CBUF_SIZE th report is received while copying of the Nth report->value is in progress, the pointer that copy_to_user() is working on is kfree()ed and UAF read may occur. (race condition) Since the device node of this driver does not set separate permissions, this is not a security vulnerability, but because it is used for requesting screen display of profile or dpi settings, a user using the roccat device can apply udev to this device node or There is a possibility to use it by giving. Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com> --- drivers/hid/hid-roccat.c | 4 ++++ 1 file changed, 4 insertions(+)