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genhd: check for int overflow in disk_expand_part_tbl()

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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>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Jens Axboe 2014-11-19 13:06:22 -07:00
parent 7c7f2f2bc9
commit 5fabcb4c33
1 changed files with 9 additions and 2 deletions
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11
block/genhd.c
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@ -1070,9 +1070,16 @@ int disk_expand_part_tbl(struct gendisk *disk, int partno)
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))