From: Nikos Tsironis Date: Fri, 27 Mar 2020 14:01:09 +0000 (+0200) Subject: dm clone: Add overflow check for number of regions X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=cd481c12269b4d276f1a52eda0ebd419079bfe3a;p=linux.git dm clone: Add overflow check for number of regions Add overflow check for clone->nr_regions variable, which holds the number of regions of the target. The overflow can occur with sufficiently large devices, if BITS_PER_LONG == 32. E.g., if the region size is 8 sectors (4K), the overflow would occur for device sizes > 34359738360 sectors (~16TB). This could result in multiple device sectors wrongly mapping to the same region number, due to the truncation from 64 bits to 32 bits, which would lead to data corruption. Fixes: 7431b7835f55 ("dm: add clone target") Cc: stable@vger.kernel.org # v5.4+ Signed-off-by: Nikos Tsironis Signed-off-by: Mike Snitzer --- diff --git a/drivers/md/dm-clone-target.c b/drivers/md/dm-clone-target.c index 022dddcad6474..6ee85fb3388ab 100644 --- a/drivers/md/dm-clone-target.c +++ b/drivers/md/dm-clone-target.c @@ -1790,6 +1790,7 @@ error: static int clone_ctr(struct dm_target *ti, unsigned int argc, char **argv) { int r; + sector_t nr_regions; struct clone *clone; struct dm_arg_set as; @@ -1831,7 +1832,16 @@ static int clone_ctr(struct dm_target *ti, unsigned int argc, char **argv) goto out_with_source_dev; clone->region_shift = __ffs(clone->region_size); - clone->nr_regions = dm_sector_div_up(ti->len, clone->region_size); + nr_regions = dm_sector_div_up(ti->len, clone->region_size); + + /* Check for overflow */ + if (nr_regions != (unsigned long)nr_regions) { + ti->error = "Too many regions. Consider increasing the region size"; + r = -EOVERFLOW; + goto out_with_source_dev; + } + + clone->nr_regions = nr_regions; r = validate_nr_regions(clone->nr_regions, &ti->error); if (r)