diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2021-12-31 21:07:12 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-01-16 09:15:38 +0100 |
| commit | 1199f0928488199c30ade617cecccdf606a92fd2 (patch) | |
| tree | 91ce17201d8257dfbd57f2128b95ceccc39a1903 | |
| parent | 43aac50196f3214def6a313e65079babb5c7f047 (diff) | |
USB: Fix "slab-out-of-bounds Write" bug in usb_hcd_poll_rh_status
commit 1d7d4c07932e04355d6e6528d44a2f2c9e354346 upstream.
When the USB core code for getting root-hub status reports was
originally written, it was assumed that the hub driver would be its
only caller. But this isn't true now; user programs can use usbfs to
communicate with root hubs and get status reports. When they do this,
they may use a transfer_buffer that is smaller than the data returned
by the HCD, which will lead to a buffer overflow error when
usb_hcd_poll_rh_status() tries to store the status data. This was
discovered by syzbot:
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/fortify-string.h:225 [inline]
BUG: KASAN: slab-out-of-bounds in usb_hcd_poll_rh_status+0x5f4/0x780 drivers/usb/core/hcd.c:776
Write of size 2 at addr ffff88801da403c0 by task syz-executor133/4062
This patch fixes the bug by reducing the amount of status data if it
won't fit in the transfer_buffer. If some data gets discarded then
the URB's completion status is set to -EOVERFLOW rather than 0, to let
the user know what happened.
Reported-and-tested-by: syzbot+3ae6a2b06f131ab9849f@syzkaller.appspotmail.com
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/Yc+3UIQJ2STbxNua@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/core/hcd.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c index d0f45600b669..fe9b392bffee 100644 --- a/drivers/usb/core/hcd.c +++ b/drivers/usb/core/hcd.c @@ -753,6 +753,7 @@ void usb_hcd_poll_rh_status(struct usb_hcd *hcd) { struct urb *urb; int length; + int status; unsigned long flags; char buffer[6]; /* Any root hubs with > 31 ports? */ @@ -770,11 +771,17 @@ void usb_hcd_poll_rh_status(struct usb_hcd *hcd) if (urb) { clear_bit(HCD_FLAG_POLL_PENDING, &hcd->flags); hcd->status_urb = NULL; + if (urb->transfer_buffer_length >= length) { + status = 0; + } else { + status = -EOVERFLOW; + length = urb->transfer_buffer_length; + } urb->actual_length = length; memcpy(urb->transfer_buffer, buffer, length); usb_hcd_unlink_urb_from_ep(hcd, urb); - usb_hcd_giveback_urb(hcd, urb, 0); + usb_hcd_giveback_urb(hcd, urb, status); } else { length = 0; set_bit(HCD_FLAG_POLL_PENDING, &hcd->flags); |