On Fri, Aug 27, 2010 at 02:02:41PM -0700, Kees Cook wrote: > This problem was originally tracked down by Brad Spengler. > > When calling wireless ioctls, if a driver does not correctly > validate/shrink iwp->length, the resulting copy_to_user can leak up to > 64K of kernel heap contents. > > It seems that this is triggerable[1] in 2.6.32 at least on ath5k, but > I was not able to track down how. The twisty maze of ioctl handlers > stumped me. :) You can always ask. > Other drivers I checked did not appear to have any problems, > but the potential remains. I'm not sure if this patch is the right approach; > it was fixed differently[2] in grsecurity. Did you tried your patch for real ? With large scan request ? I ask because at first glance, it looks incorrect, asI believe it kills large request. But someone would need to test, for sure. > [1] http://forums.grsecurity.net/viewtopic.php?f=3&t=2290&start=0 > [2] http://grsecurity.net/~spender/wireless-infoleak-fix2.patch I believe this patch would make the situation worse. Would you mind validating the following patch ? I've just verified that it compiles and I believe it does what you are asking in a much more predictable way. Regards, Jean Signed-off-by: Jean Tourrilhes <jt@xxxxxxxxxx> diff -u -p wext.j2.c wext.c --- wext.j2.c 2010-08-27 14:17:26.000000000 -0700 +++ wext.c 2010-08-27 14:19:33.000000000 -0700 @@ -800,9 +800,12 @@ static int ioctl_standard_iw_point(struc goto out; } - if (copy_to_user(iwp->pointer, extra, - iwp->length * - descr->token_size)) { + /* Verify how much we should return. Some driver + * may abuse iwp->length... */ + if((iwp->length * descr->token_size) < extra_size) + extra_size = iwp->length * descr->token_size; + + if (copy_to_user(iwp->pointer, extra, extra_size)) { err = -EFAULT; goto out; } -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
