* [PATCH][RESEND] mac: validate mac_partition is within sector
@ 2015-11-20 1:18 Kees Cook
2015-11-20 21:31 ` Jeff Moyer
0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2015-11-20 1:18 UTC (permalink / raw)
To: Andrew Morton; +Cc: Jens Axboe, Dan Carpenter, linux-block, linux-kernel
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
---
There doesn't seem to be a mac partition maintainer...
---
block/partitions/mac.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/block/partitions/mac.c b/block/partitions/mac.c
index c2c48ec64b27..621317ac4d59 100644
--- a/block/partitions/mac.c
+++ b/block/partitions/mac.c
@@ -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, §);
+ datasize = round_down(secsize, 512);
+ data = read_part_sector(state, datasize / 512, §);
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 */
--
1.9.1
--
Kees Cook
Chrome OS Security
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH][RESEND] mac: validate mac_partition is within sector
2015-11-20 1:18 [PATCH][RESEND] mac: validate mac_partition is within sector Kees Cook
@ 2015-11-20 21:31 ` Jeff Moyer
0 siblings, 0 replies; 2+ messages in thread
From: Jeff Moyer @ 2015-11-20 21:31 UTC (permalink / raw)
To: Kees Cook
Cc: Andrew Morton, Jens Axboe, Dan Carpenter, linux-block, linux-kernel
Kees Cook <keescook@chromium.org> writes:
> 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).
Do we even want to support non-power-of-two block sizes?
-Jeff
>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Cc: stable@vger.kernel.org
> ---
> There doesn't seem to be a mac partition maintainer...
> ---
> block/partitions/mac.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/block/partitions/mac.c b/block/partitions/mac.c
> index c2c48ec64b27..621317ac4d59 100644
> --- a/block/partitions/mac.c
> +++ b/block/partitions/mac.c
> @@ -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, §);
> + datasize = round_down(secsize, 512);
> + data = read_part_sector(state, datasize / 512, §);
> 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 */
> --
> 1.9.1
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