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path: root/drivers/hid/uhid.c
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Diffstat (limited to 'drivers/hid/uhid.c')
-rw-r--r--drivers/hid/uhid.c25
1 files changed, 19 insertions, 6 deletions
diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c
index 3c5507313606..840634e0f1e3 100644
--- 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: