Merge tag 'drm-intel-next-2018-12-04' of git://anongit.freedesktop.org/drm/drm-intel...

[sfrench/cifs-2.6.git] / drivers / hid / uhid.c

diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c
index 3c55073136064263c0b1175cbcce60acd81d34ba..840634e0f1e3cc46235cf456a04e547f2be65ba8 100644 (file)
--- a/drivers/hid/uhid.c
+++ b/drivers/hid/uhid.c
@@ -12,6 +12,7 @@
 
 #include <linux/atomic.h>
 #include <linux/compat.h>
+#include <linux/cred.h>
 #include <linux/device.h>
 #include <linux/fs.h>
 #include <linux/hid.h>
@@ -496,12 +497,13 @@ static int uhid_dev_create2(struct uhid_device *uhid,
                goto err_free;
        }
 
-       len = min(sizeof(hid->name), sizeof(ev->u.create2.name));
-       strlcpy(hid->name, ev->u.create2.name, len);
-       len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys));
-       strlcpy(hid->phys, ev->u.create2.phys, len);
-       len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq));
-       strlcpy(hid->uniq, ev->u.create2.uniq, len);
+       /* @hid is zero-initialized, strncpy() is correct, strlcpy() not */
+       len = min(sizeof(hid->name), sizeof(ev->u.create2.name)) - 1;
+       strncpy(hid->name, ev->u.create2.name, len);
+       len = min(sizeof(hid->phys), sizeof(ev->u.create2.phys)) - 1;
+       strncpy(hid->phys, ev->u.create2.phys, len);
+       len = min(sizeof(hid->uniq), sizeof(ev->u.create2.uniq)) - 1;
+       strncpy(hid->uniq, ev->u.create2.uniq, len);
 
        hid->ll_driver = &uhid_hid_driver;
        hid->bus = ev->u.create2.bus;
@@ -722,6 +724,17 @@ static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
 
        switch (uhid->input_buf.type) {
        case UHID_CREATE:
+               /*
+                * 'struct uhid_create_req' contains a __user pointer which is
+                * copied from, so it's unsafe to allow this with elevated
+                * privileges (e.g. from a setuid binary) or via kernel_write().
+                */
+               if (file->f_cred != current_cred() || uaccess_kernel()) {
+                       pr_err_once("UHID_CREATE from different security context by process %d (%s), this is not allowed.\n",
+                                   task_tgid_vnr(current), current->comm);
+                       ret = -EACCES;
+                       goto unlock;
+               }
                ret = uhid_dev_create(uhid, &uhid->input_buf);
                break;
        case UHID_CREATE2: