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| author | Dan Carpenter <dan.carpenter@oracle.com> | 2017-09-22 23:43:25 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-09-25 10:57:13 +0200 |
| commit | 57999d1107c1e60c2ca7088f2ac0f819e2f554b3 (patch) | |
| tree | 6081b8b694eeae7c08ea2cc082c9966517cdb838 /drivers/usb/core/devio.c | |
| parent | 1fbbb78f25d1291274f320462bf6908906f538db (diff) | |
| download | linux-57999d1107c1e60c2ca7088f2ac0f819e2f554b3.tar.bz2 | |
USB: devio: Prevent integer overflow in proc_do_submiturb()
There used to be an integer overflow check in proc_do_submiturb() but
we removed it. It turns out that it's still required. The
uurb->buffer_length variable is a signed integer and it's controlled by
the user. It can lead to an integer overflow when we do:
num_sgs = DIV_ROUND_UP(uurb->buffer_length, USB_SG_SIZE);
If we strip away the macro then that line looks like this:
num_sgs = (uurb->buffer_length + USB_SG_SIZE - 1) / USB_SG_SIZE;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
It's the first addition which can overflow.
Fixes: 1129d270cbfb ("USB: Increase usbfs transfer limit")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core/devio.c')
| -rw-r--r-- | drivers/usb/core/devio.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 318bb3b96687..e9326f31db8d 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -140,6 +140,9 @@ module_param(usbfs_memory_mb, uint, 0644); MODULE_PARM_DESC(usbfs_memory_mb, "maximum MB allowed for usbfs buffers (0 = no limit)"); +/* Hard limit, necessary to avoid arithmetic overflow */ +#define USBFS_XFER_MAX (UINT_MAX / 2 - 1000000) + static atomic64_t usbfs_memory_usage; /* Total memory currently allocated */ /* Check whether it's okay to allocate more memory for a transfer */ @@ -1460,6 +1463,8 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb USBDEVFS_URB_ZERO_PACKET | USBDEVFS_URB_NO_INTERRUPT)) return -EINVAL; + if ((unsigned int)uurb->buffer_length >= USBFS_XFER_MAX) + return -EINVAL; if (uurb->buffer_length > 0 && !uurb->buffer) return -EINVAL; if (!(uurb->type == USBDEVFS_URB_TYPE_CONTROL && |