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authorHyunwoo Kim <imv4bel@gmail.com>2022-09-04 12:31:15 -0700
committerJiri Kosina <jkosina@suse.cz>2022-09-20 14:49:15 +0200
commitcacdb14b1c8d3804a3a7d31773bc7569837b71a4 (patch)
tree31a7419069220bbd8d6c8ea3f8c4bbab87574b92 /drivers/hid
parent0627f3df95e1609693f89e7ceb4156ac5db6e358 (diff)
HID: roccat: Fix use-after-free in roccat_read()
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> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid')
-rw-r--r--drivers/hid/hid-roccat.c4
1 files changed, 4 insertions, 0 deletions
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;
}