mac: validate mac_partition is within sector
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>
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@ -32,7 +32,7 @@ int mac_partition(struct parsed_partitions *state)
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Sector sect;
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unsigned char *data;
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int slot, blocks_in_map;
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unsigned secsize;
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unsigned secsize, datasize, partoffset;
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#ifdef CONFIG_PPC_PMAC
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int found_root = 0;
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int found_root_goodness = 0;
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@ -50,10 +50,14 @@ int mac_partition(struct parsed_partitions *state)
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}
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secsize = be16_to_cpu(md->block_size);
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put_dev_sector(sect);
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data = read_part_sector(state, secsize/512, §);
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datasize = round_down(secsize, 512);
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data = read_part_sector(state, datasize / 512, §);
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if (!data)
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return -1;
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part = (struct mac_partition *) (data + secsize%512);
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partoffset = secsize % 512;
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if (partoffset + sizeof(*part) > datasize)
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return -1;
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part = (struct mac_partition *) (data + partoffset);
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if (be16_to_cpu(part->signature) != MAC_PARTITION_MAGIC) {
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put_dev_sector(sect);
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return 0; /* not a MacOS disk */
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