| Message ID | 4B699DB6.4090604@cisco.com |
|---|---|
| State | New |
| Headers | show |
I have not seen response to this. If there are no objections please apply. Thanks, David Ahern On 02/03/2010 09:00 AM, David S. Ahern wrote: > This fixes a segfault due to buffer overrun in the usb-serial device. > The memcpy was incrementing the start location by recv_used yet, the > computation of first_size (how much to write at the end of the buffer > before wrapping to the front) was not accounting for it. This causes the > next element after the receive buffer (recv_ptr) to get overwritten with > random data. > > Signed-off-by: David Ahern <daahern@cisco.com> > > diff --git a/hw/usb-serial.c b/hw/usb-serial.c > index 37293ea..c3f3401 100644 > --- a/hw/usb-serial.c > +++ b/hw/usb-serial.c > @@ -497,12 +497,28 @@ static int usb_serial_can_read(void *opaque) > static void usb_serial_read(void *opaque, const uint8_t *buf, int size) > { > USBSerialState *s = opaque; > - int first_size = RECV_BUF - s->recv_ptr; > - if (first_size > size) > - first_size = size; > - memcpy(s->recv_buf + s->recv_ptr + s->recv_used, buf, first_size); > - if (size > first_size) > - memcpy(s->recv_buf, buf + first_size, size - first_size); > + int first_size, start; > + > + /* room in the buffer? */ > + if (size > (RECV_BUF - s->recv_used)) > + size = RECV_BUF - s->recv_used; > + > + start = s->recv_ptr + s->recv_used; > + if (start < RECV_BUF) { > + /* copy data to end of buffer */ > + first_size = RECV_BUF - start; > + if (first_size > size) > + first_size = size; > + > + memcpy(s->recv_buf + start, buf, first_size); > + > + /* wrap around to front if needed */ > + if (size > first_size) > + memcpy(s->recv_buf, buf + first_size, size - first_size); > + } else { > + start -= RECV_BUF; > + memcpy(s->recv_buf + start, buf, size); > + } > s->recv_used += size; > } > > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
On 02/03/2010 10:00 AM, David S. Ahern wrote: > This fixes a segfault due to buffer overrun in the usb-serial device. > The memcpy was incrementing the start location by recv_used yet, the > computation of first_size (how much to write at the end of the buffer > before wrapping to the front) was not accounting for it. This causes the > next element after the receive buffer (recv_ptr) to get overwritten with > random data. > > Signed-off-by: David Ahern<daahern@cisco.com> > Applied. Thanks. Regards, Anthony Liguori > diff --git a/hw/usb-serial.c b/hw/usb-serial.c > index 37293ea..c3f3401 100644 > --- a/hw/usb-serial.c > +++ b/hw/usb-serial.c > @@ -497,12 +497,28 @@ static int usb_serial_can_read(void *opaque) > static void usb_serial_read(void *opaque, const uint8_t *buf, int size) > { > USBSerialState *s = opaque; > - int first_size = RECV_BUF - s->recv_ptr; > - if (first_size> size) > - first_size = size; > - memcpy(s->recv_buf + s->recv_ptr + s->recv_used, buf, first_size); > - if (size> first_size) > - memcpy(s->recv_buf, buf + first_size, size - first_size); > + int first_size, start; > + > + /* room in the buffer? */ > + if (size> (RECV_BUF - s->recv_used)) > + size = RECV_BUF - s->recv_used; > + > + start = s->recv_ptr + s->recv_used; > + if (start< RECV_BUF) { > + /* copy data to end of buffer */ > + first_size = RECV_BUF - start; > + if (first_size> size) > + first_size = size; > + > + memcpy(s->recv_buf + start, buf, first_size); > + > + /* wrap around to front if needed */ > + if (size> first_size) > + memcpy(s->recv_buf, buf + first_size, size - first_size); > + } else { > + start -= RECV_BUF; > + memcpy(s->recv_buf + start, buf, size); > + } > s->recv_used += size; > } > > > > > >
diff --git a/hw/usb-serial.c b/hw/usb-serial.c index 37293ea..c3f3401 100644 --- a/hw/usb-serial.c +++ b/hw/usb-serial.c @@ -497,12 +497,28 @@ static int usb_serial_can_read(void *opaque) static void usb_serial_read(void *opaque, const uint8_t *buf, int size) { USBSerialState *s = opaque; - int first_size = RECV_BUF - s->recv_ptr; - if (first_size > size) - first_size = size; - memcpy(s->recv_buf + s->recv_ptr + s->recv_used, buf, first_size); - if (size > first_size) - memcpy(s->recv_buf, buf + first_size, size - first_size); + int first_size, start; + + /* room in the buffer? */ + if (size > (RECV_BUF - s->recv_used)) + size = RECV_BUF - s->recv_used; + + start = s->recv_ptr + s->recv_used; + if (start < RECV_BUF) { + /* copy data to end of buffer */ + first_size = RECV_BUF - start; + if (first_size > size) + first_size = size; + + memcpy(s->recv_buf + start, buf, first_size); + + /* wrap around to front if needed */ + if (size > first_size) + memcpy(s->recv_buf, buf + first_size, size - first_size); + } else { + start -= RECV_BUF; + memcpy(s->recv_buf + start, buf, size); + } s->recv_used += size; }
This fixes a segfault due to buffer overrun in the usb-serial device. The memcpy was incrementing the start location by recv_used yet, the computation of first_size (how much to write at the end of the buffer before wrapping to the front) was not accounting for it. This causes the next element after the receive buffer (recv_ptr) to get overwritten with random data. Signed-off-by: David Ahern <daahern@cisco.com>