lkml.org 
[lkml]   [2006]   [Jun]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [Patch] Off by one in drivers/usb/serial/usb-serial.c
* Mikael Pettersson (mikpe@it.uu.se) wrote:
> On Wed, 21 Jun 2006 23:28:17 +0200, Eric Sesterhenn wrote:
> > this fixes coverity id #554. since serial table
> > is defines as serial_table[SERIAL_TTY_MINORS] we
> > should make sure we dont acess with an index
> > of SERIAL_TTY_MINORS.
> >
> > Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
> >
> > --- linux-2.6.17-git2/drivers/usb/serial/usb-serial.c.orig 2006-06-21 23:24:07.000000000 +0200
> > +++ linux-2.6.17-git2/drivers/usb/serial/usb-serial.c 2006-06-21 23:25:12.000000000 +0200
> > @@ -83,7 +83,7 @@ static struct usb_serial *get_free_seria
> >
> > good_spot = 1;
> > for (j = 1; j <= num_ports-1; ++j)
> > - if ((i+j >= SERIAL_TTY_MINORS) || (serial_table[i+j])) {
> > + if ((i+j >= SERIAL_TTY_MINORS-1)||(serial_table[i+j])) {
> > good_spot = 0;
> > i += j;
> > break;
>
> Where is the access coverity complained about? If it's the serial_table[i+j]
> quoted above, then the original code is OK since i+j < SERIAL_TTY_MINORS is
> an invariant in that subexpression.
>
> And the other accesses to serial_table[] in get_free_serial() are also only
> done when the index is < SERIAL_TTY_MINORS.

guess i was too quick on that one, sorry. Here is the coverity
report for completeness.

Event assignment: Assigning "1" to "j"
Also see events: [overrun-local]
At conditional (11): "j <= (num_ports - 1)" taking true path
At conditional (16): "j <= (num_ports - 1)" taking true path

85 for (j = 1; j <= num_ports-1; ++j)

Event overrun-local: Overrun of static array "serial_table" of size 255
at position 255 with index variable "(i + j)"
Also see events: [assignment]
At conditional (12): "(i + j) >= 255" taking true path
At conditional (17): "(i + j) >= 255" taking false path

86 if ((i+j >= SERIAL_TTY_MINORS) ||
(serial_table[i+j])) {
87 good_spot = 0;
88 i += j;
89 break;
90 }



greetings, Eric

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-06-26 01:01    [W:0.070 / U:1.232 seconds]
©2003-2014 Jasper Spaans. Advertise on this site