| From | Andi Kleen <> | Subject | [PATCH] [222/223] Fix pktcdvd ioctl dev_minor range check | Date | Mon, 13 Dec 2010 00:48:50 +0100 (CET) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Dan Rosenberg <drosenberg@vsecurity.com>
Upstream 252a52aa4fa22a668f019e55b3aac3ff71ec1c29
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> Signed-off-by: Andi Kleen <ak@linux.intel.com> --- drivers/block/pktcdvd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux/drivers/block/pktcdvd.c =================================================================== --- linux.orig/drivers/block/pktcdvd.c +++ linux/drivers/block/pktcdvd.c @@ -2368,7 +2368,7 @@ static void pkt_release_dev(struct pktcd 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;
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