diff options
author | Alan Stern <stern@rowland.harvard.edu> | 2019-04-15 11:51:38 -0400 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-08 07:19:08 +0200 |
commit | 7bbbb95a4b5729f5601938ac7d37394c1ba5e30e (patch) | |
tree | aa86083f2845a353094fcc90125aa021824cd4c6 | |
parent | 616ba129e17606f485dc325e0eef745c5e069e48 (diff) |
USB: core: Fix unterminated string returned by usb_string()
commit c01c348ecdc66085e44912c97368809612231520 upstream.
Some drivers (such as the vub300 MMC driver) expect usb_string() to
return a properly NUL-terminated string, even when an error occurs.
(In fact, vub300's probe routine doesn't bother to check the return
code from usb_string().) When the driver goes on to use an
unterminated string, it leads to kernel errors such as
stack-out-of-bounds, as found by the syzkaller USB fuzzer.
An out-of-range string index argument is not at all unlikely, given
that some devices don't provide string descriptors and therefore list
0 as the value for their string indexes. This patch makes
usb_string() return a properly terminated empty string along with the
-EINVAL error code when an out-of-range index is encountered.
And since a USB string index is a single-byte value, indexes >= 256
are just as invalid as values of 0 or below.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: syzbot+b75b85111c10b8d680f1@syzkaller.appspotmail.com
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/usb/core/message.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index 0e6ab0a17c08..955cd6552e95 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -817,9 +817,11 @@ int usb_string(struct usb_device *dev, int index, char *buf, size_t size) if (dev->state == USB_STATE_SUSPENDED) return -EHOSTUNREACH; - if (size <= 0 || !buf || !index) + if (size <= 0 || !buf) return -EINVAL; buf[0] = 0; + if (index <= 0 || index >= 256) + return -EINVAL; tbuf = kmalloc(256, GFP_NOIO); if (!tbuf) return -ENOMEM; |