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mac: validate mac_partition is within sector

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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).

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Kees Cook 2015-11-19 17:18:54 -08:00 committed by Jens Axboe
parent 8aeea03195
commit 02e2a5bfeb
1 changed files with 7 additions and 3 deletions
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10
block/partitions/mac.c
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@ -32,7 +32,7 @@ int mac_partition(struct parsed_partitions *state)
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_partitions *state)
}
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 */