diff mbox series

[4.19,124/125] HID: hiddev: Fix slab-out-of-bounds write in hiddev_ioctl_usage()

Message ID 20200901150940.687698839@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg KH Sept. 1, 2020, 3:11 p.m. UTC 
From: Peilin Ye <yepeilin.cs@gmail.com>

commit 25a097f5204675550afb879ee18238ca917cba7a upstream.

`uref->usage_index` is not always being properly checked, causing
hiddev_ioctl_usage() to go out of bounds under some cases. Fix it.

Reported-by: syzbot+34ee1b45d88571c2fa8b@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=f2aebe90b8c56806b050a20b36f51ed6acabe802
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hid/usbhid/hiddev.c |    4 ++++
 1 file changed, 4 insertions(+)

Comments

Dan Carpenter Sept. 1, 2020, 7:36 p.m. UTC | #1 
On Tue, Sep 01, 2020 at 09:12:09PM +0200, Pavel Machek wrote:
> Hi!
> 
> > commit 25a097f5204675550afb879ee18238ca917cba7a upstream.
> > 
> > `uref->usage_index` is not always being properly checked, causing
> > hiddev_ioctl_usage() to go out of bounds under some cases. Fix it.
> 
> Well, the code is quite confusig, but:
> 
> a) does HIDIOCGCOLLECTIONINDEX need same checking?

It's checked in the previous switch statement.

> 
> b) should we check this using some kind of _nospec() variant to
> prevent speculation attacks?

I don't think so.  I wrote up an explanation earlier just because the
code was so confusing.

https://lkml.org/lkml/2020/7/20/523

regards,
dan carpenter
diff mbox series

Patch

--- a/drivers/hid/usbhid/hiddev.c
+++ b/drivers/hid/usbhid/hiddev.c
@@ -532,12 +532,16 @@  static noinline int hiddev_ioctl_usage(s
 
 		switch (cmd) {
 		case HIDIOCGUSAGE:
+			if (uref->usage_index >= field->report_count)
+				goto inval;
 			uref->value = field->value[uref->usage_index];
 			if (copy_to_user(user_arg, uref, sizeof(*uref)))
 				goto fault;
 			goto goodreturn;
 
 		case HIDIOCSUSAGE:
+			if (uref->usage_index >= field->report_count)
+				goto inval;
 			field->value[uref->usage_index] = uref->value;
 			goto goodreturn;