Check on-disk chunk size. The previous code blindly used the chunk size stored on disk. This is wrong because it can lead to a crash if the disk storage is corrupted. See https://bugzilla.redhat.com/show_bug.cgi?id=461506 This code passes on-disk size through similar checks as size specified on the table argument line, thus it won't allow to use bogus values (such as zero, in case of that bug). Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> --- drivers/md/dm-snap-persistent.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) Index: linux-2.6.31-rc5-devel/drivers/md/dm-snap-persistent.c =================================================================== --- linux-2.6.31-rc5-devel.orig/drivers/md/dm-snap-persistent.c 2009-08-04 03:20:11.000000000 +0200 +++ linux-2.6.31-rc5-devel/drivers/md/dm-snap-persistent.c 2009-08-04 03:24:16.000000000 +0200 @@ -283,6 +283,7 @@ static int read_header(struct pstore *ps struct disk_header *dh; chunk_t chunk_size; int chunk_size_supplied = 1; + char *chunk_err; /* * Use default chunk size (or hardsect_size, if larger) if none supplied @@ -326,20 +327,23 @@ static int read_header(struct pstore *ps ps->version = le32_to_cpu(dh->version); chunk_size = le32_to_cpu(dh->chunk_size); - if (!chunk_size_supplied || ps->store->chunk_size == chunk_size) + if (ps->store->chunk_size == chunk_size) return 0; - DMWARN("chunk size %llu in device metadata overrides " - "table chunk size of %llu.", - (unsigned long long)chunk_size, - (unsigned long long)ps->store->chunk_size); + if (chunk_size_supplied) + DMWARN("chunk size %llu in device metadata overrides " + "table chunk size of %llu.", + (unsigned long long)chunk_size, + (unsigned long long)ps->store->chunk_size); /* We had a bogus chunk_size. Fix stuff up. */ free_area(ps); - ps->store->chunk_size = chunk_size; - ps->store->chunk_mask = chunk_size - 1; - ps->store->chunk_shift = ffs(chunk_size) - 1; + r = dm_exception_store_set_chunk_size(ps->store, chunk_size, &chunk_err); + if (r) { + DMERR("invalid on-disk chunk size %llu: %s.", (unsigned long long)chunk_size, chunk_err); + return r; + } r = dm_io_client_resize(sectors_to_pages(ps->store->chunk_size), ps->io_client); -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
