| From | Ben Hutchings <> | Date | Tue, 17 Feb 2015 01:46:53 +0000 | Subject | [PATCH 3.2 018/152] genhd: check for int overflow in disk_expand_part_tbl() |
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3.2.67-rc1 review patch. If anyone has any objections, please let me know.
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From: Jens Axboe <axboe@fb.com>
commit 5fabcb4c33fe11c7e3afdf805fde26c1a54d0953 upstream.
We can get here from blkdev_ioctl() -> blkpg_ioctl() -> add_partition() with a user passed in partno value. If we pass in 0x7fffffff, the new target in disk_expand_part_tbl() overflows the 'int' and we access beyond the end of ptbl->part[] and even write to it when we do the rcu_assign_pointer() to assign the new partition.
Reported-by: David Ramos <daramos@stanford.edu> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- block/genhd.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/block/genhd.c +++ b/block/genhd.c @@ -1070,9 +1070,16 @@ int disk_expand_part_tbl(struct gendisk struct disk_part_tbl *old_ptbl = disk->part_tbl; struct disk_part_tbl *new_ptbl; int len = old_ptbl ? old_ptbl->len : 0; - int target = partno + 1; + int i, target; size_t size; - int i; + + /* + * check for int overflow, since we can get here from blkpg_ioctl() + * with a user passed 'partno'. + */ + target = partno + 1; + if (target < 0) + return -EINVAL; /* disk_max_parts() is zero during initialization, ignore if so */ if (disk_max_parts(disk) && target > disk_max_parts(disk))
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