This is a note to let you know that I've just added the patch titled
USB: core: Fix unterminated string returned by usb_string()
to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From c01c348ecdc66085e44912c97368809612231520 Mon Sep 17 00:00:00 2001
From: Alan Stern stern@rowland.harvard.edu Date: Mon, 15 Apr 2019 11:51:38 -0400 Subject: USB: core: Fix unterminated string returned by usb_string()
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 --- drivers/usb/core/message.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index 82239f27c4cc..e844bb7b5676 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -820,9 +820,11 @@ 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;