CVE request - kernel: pktcdvd ioctl dev_minor missing range check

[Eugene Teo <eugeneteo () kernel sg>]

As Dan Rosenberg explained in the patch commit: The PKT_CTRL_CMD_STATUS 
device ioctl retrieves a pointer to a pktcdvd_device from the global 
pkt_devs array.  The index into this array is provided directly by the 
user and is a signed integer, so the comparison to ensure that it falls 
within the bounds of this array will fail when provided with a negative 
index.

This can be used to read arbitrary kernel memory or cause a crash due to 
an invalid pointer dereference.  This can be exploited by users with 
permission to open /dev/pktcdvd/control (on many distributions, this is 
readable by group "cdrom").

https://bugzilla.redhat.com/show_bug.cgi?id=638085
http://git.kernel.org/linus/252a52aa4fa22a668f019e55b3aac3ff71ec1c29

This was introduced in 2f8e2dc8 (v2.6.10-rc1).

Thanks, Eugene
--
main(i) { putchar(182623909 >> (i-1) * 5&31|!!(i<7)<<6) && main(++i); }