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[PATCH] dm stripe: Fix bounds 

The dm-stripe target currently does not enforce that the size of a stripe
device be a multiple of the chunk-size.  Under certain conditions, this can
lead to I/O requests going off the end of an underlying device.  This
test-case shows one example.

echo "0 100 linear /dev/hdb1 0" | dmsetup create linear0
echo "0 100 linear /dev/hdb1 100" | dmsetup create linear1
echo "0 200 striped 2 32 /dev/mapper/linear0 0 /dev/mapper/linear1 0" | \
   dmsetup create stripe0
dd if=/dev/zero of=/dev/mapper/stripe0 bs=1k

This will produce the output:
dd: writing '/dev/mapper/stripe0': Input/output error
97+0 records in
96+0 records out

And in the kernel log will be:
attempt to access beyond end of device
dm-0: rw=0, want=104, limit=100

The patch will check that the table size is a multiple of the stripe
chunk-size when the table is created, which will prevent the above striped
device from being created.

This should not affect tools like LVM or EVMS, since in all the cases I can
think of, striped devices are always created with the sizes being a
multiple of the chunk-size.

The size of a stripe device must be a multiple of its chunk-size.

(akpm: that typecast is quite gratuitous)

Signed-off-by: Kevin Corry <kevcorry@us.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Kevin Corry 2006-03-16 23:04:03 -08:00 committed by Linus Torvalds
parent 82c3c03a40
commit 8ba32fde2c
1 changed files with 7 additions and 1 deletions
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8
drivers/md/dm-stripe.c
View File

@ -103,9 +103,15 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
return -EINVAL;
}
if (((uint32_t)ti->len) & (chunk_size - 1)) {
ti->error = "dm-stripe: Target length not divisible by "
"chunk size";
return -EINVAL;
}
width = ti->len;
if (sector_div(width, stripes)) {
ti->error = "dm-stripe: Target length not divisable by "
ti->error = "dm-stripe: Target length not divisible by "
"number of stripes";
return -EINVAL;
}