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Fix pktcdvd ioctl dev_minor range check

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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").

Signed-off-by: Dan Rosenberg <dan.j.rosenberg@gmail.com>
[ Rather than add a cast, just make the function take the right type -Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Rosenberg 2010-09-27 12:30:28 -04:00 committed by Linus Torvalds
parent 95929eff2c
commit 252a52aa4f
1 changed files with 1 additions and 1 deletions
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2
drivers/block/pktcdvd.c
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@ -2369,7 +2369,7 @@ static void pkt_release_dev(struct pktcdvd_device *pd, int flush)
pkt_shrink_pktlist(pd);
}
static struct pktcdvd_device *pkt_find_dev_from_minor(int dev_minor)
static struct pktcdvd_device *pkt_find_dev_from_minor(unsigned int dev_minor)
{
if (dev_minor >= MAX_WRITERS)
return NULL;