[PATCH] fs: btrfs: fix potential overflow

From: Brian Norris
Date: Sun Aug 24 2014 - 01:41:50 EST


It looks like this intended to be 64-bit arithmetic, but it's actually
performed as 32-bit. Fix that. (Note that 'increment' was being
initialized twice, so this patch removes one of those.)

Caught by Coverity Scan (CID 1201422).

Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx>
---
Untested

fs/btrfs/scrub.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index b6d198f5181e..b1a8127737b4 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -2320,26 +2320,26 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
do_div(nstripes, map->stripe_len);
if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
offset = map->stripe_len * num;
- increment = map->stripe_len * map->num_stripes;
+ increment *= map->num_stripes;
mirror_num = 1;
} else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
int factor = map->num_stripes / map->sub_stripes;
offset = map->stripe_len * (num / map->sub_stripes);
- increment = map->stripe_len * factor;
+ increment *= factor;
mirror_num = num % map->sub_stripes + 1;
} else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
- increment = map->stripe_len;
+ increment *= 1;
mirror_num = num % map->num_stripes + 1;
} else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
- increment = map->stripe_len;
+ increment *= 1;
mirror_num = num % map->num_stripes + 1;
} else if (map->type & (BTRFS_BLOCK_GROUP_RAID5 |
BTRFS_BLOCK_GROUP_RAID6)) {
get_raid56_logic_offset(physical, num, map, &offset);
- increment = map->stripe_len * nr_data_stripes(map);
+ increment *= nr_data_stripes(map);
mirror_num = 1;
} else {
- increment = map->stripe_len;
+ increment *= 1;
mirror_num = 1;
}

--
1.7.9.5

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