4.4-stable review patch. If anyone has any objections, please let me know.
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From: Dan Carpenter dan.carpenter@oracle.com
commit 57999d1107c1e60c2ca7088f2ac0f819e2f554b3 upstream.
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") 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
--- drivers/usb/core/devio.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -118,6 +118,9 @@ 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 */ @@ -1298,6 +1301,8 @@ static int proc_do_submiturb(struct usb_ 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 &&