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usb-linux.c: fix buffer overflow

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In usb-linux.c:usb_host_handle_control, we pass a 1024-byte buffer and
length to the kernel.  However, the length was provided by the caller
of dev->handle_packet, and is not checked, so the kernel might provide
too much data and overflow our buffer.

For example, hw/usb-uhci.c could set the length to 2047.
hw/usb-ohci.c looks like it might go up to 4096 or 8192.

This causes a qemu crash, as reported here:
  http://www.mail-archive.com/kvm@vger.kernel.org/msg18447.html

This patch increases the usb-linux.c buffer size to 2048 to fix the
specific device reported, and adds a check to avoid the overflow in
any case.

Signed-off-by: Jim Paris <jim@jtan.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Jim Paris 2009-08-24 14:56:12 -04:00 committed by Anthony Liguori
parent aeec26d348
commit c4c0e236be
1 changed files with 10 additions and 2 deletions
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12
usb-linux.c
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@ -115,7 +115,7 @@ struct ctrl_struct {
uint16_t offset;
uint8_t state;
struct usb_ctrlrequest req;
uint8_t buffer[1024];
uint8_t buffer[2048];
};
typedef struct USBHostDevice {
@ -552,6 +552,7 @@ static int usb_host_handle_control(USBHostDevice *s, USBPacket *p)
struct usbdevfs_urb *urb;
AsyncURB *aurb;
int ret, value, index;
int buffer_len;
/*
* Process certain standard device requests.
@ -580,6 +581,13 @@ static int usb_host_handle_control(USBHostDevice *s, USBPacket *p)
/* The rest are asynchronous */
buffer_len = 8 + s->ctrl.len;
if (buffer_len > sizeof(s->ctrl.buffer)) {
fprintf(stderr, "husb: ctrl buffer too small (%u > %lu)\n",
buffer_len, sizeof(s->ctrl.buffer));
return USB_RET_STALL;
}
aurb = async_alloc();
aurb->hdev = s;
aurb->packet = p;
@ -596,7 +604,7 @@ static int usb_host_handle_control(USBHostDevice *s, USBPacket *p)
urb->endpoint = p->devep;
urb->buffer = &s->ctrl.req;
urb->buffer_length = 8 + s->ctrl.len;
urb->buffer_length = buffer_len;
urb->usercontext = s;