The problem is we're copying "inherit" from user space but we don't
necessarily know that we're copying enough data for a 64 byte
struct. Then the next problem is that "inherit" has a variable size
array at the end, and we have to verify that array is the size we
expected.
Fixes: 6f72c7e20dba: ("Btrfs: add qgroup inheritance")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
Presumably only root can create snapshots. Anyway, I have not tested
this fix. I believe it is correct, of course. But perhaps it's best
to check.
The calculation for the number of elements in the array was copied from
btrfs_qgroup_inherit().
fs/btrfs/ioctl.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 384d33ab02c7..9d7b24d3e3bd 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1941,15 +1941,34 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
readonly = true;
if (vol_args->flags & BTRFS_SUBVOL_QGROUP_INHERIT) {
- if (vol_args->size > PAGE_SIZE) {
+ u64 nums;
+
+ if (vol_args->size < sizeof(*inherit) ||
+ vol_args->size > PAGE_SIZE) {
ret = -EINVAL;
goto free_args;
}
+
inherit = memdup_user(vol_args->qgroup_inherit, vol_args->size);
if (IS_ERR(inherit)) {
ret = PTR_ERR(inherit);
goto free_args;
}
+
+ /* quick and dirty checks to prevent integer overflows */
+ if (inherit->num_qgroups > PAGE_SIZE ||
+ inherit->num_ref_copies > PAGE_SIZE ||
+ inherit->num_excl_copies > PAGE_SIZE) {
+ ret = -EINVAL;
+ goto free_inherit;
+ }
+
+ nums = inherit->num_qgroups + 2 * inherit->num_ref_copies +
+ 2 * inherit->num_excl_copies;
+ if (vol_args->size != struct_size(inherit, qgroups, nums)) {
+ ret = -EINVAL;
+ goto free_inherit;
+ }
}
ret = __btrfs_ioctl_snap_create(file, vol_args->name, vol_args->fd,
--
2.30.0
