Patch "mac: validate mac_partition is within sector" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

mac: validate mac_partition is within sector

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mac-validate-mac_partition-is-within-sector.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Kees Cook <[email protected]>
Date: Thu, 19 Nov 2015 17:18:54 -0800
Subject: mac: validate mac_partition is within sector

From: Kees Cook <[email protected]>

commit 02e2a5bfebe99edcf9d694575a75032d53fe1b73 upstream.

If md->signature == MAC_DRIVER_MAGIC and md->block_size == 1023, a single 512 byte sector would be read (secsize / 512). However the partition structure would be located past the end of the buffer (secsize % 512).

---
 block/partitions/mac.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

@@ -32,7 +32,7 @@ int mac_partition(struct parsed_partitio
 	Sector sect;
 	unsigned char *data;
 	int slot, blocks_in_map;
-	unsigned secsize;
+	unsigned secsize, datasize, partoffset;
 #ifdef CONFIG_PPC_PMAC
 	int found_root = 0;
 	int found_root_goodness = 0;

@@ -50,10 +50,14 @@ int mac_partition(struct parsed_partitio
 	}
 	secsize = be16_to_cpu(md->block_size);
 	put_dev_sector(sect);
-	data = read_part_sector(state, secsize/512, &sect);
+	datasize = round_down(secsize, 512);
+	data = read_part_sector(state, datasize / 512, &sect);
 	if (!data)
 		return -1;
-	part = (struct mac_partition *) (data + secsize%512);
+	partoffset = secsize % 512;
+	if (partoffset + sizeof(*part) > datasize)
+		return -1;
+	part = (struct mac_partition *) (data + partoffset);
 	if (be16_to_cpu(part->signature) != MAC_PARTITION_MAGIC) {
 		put_dev_sector(sect);
 		return 0;		/* not a MacOS disk */

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/mac-validate-mac_partition-is-within-sector.patch