[004/289] block: take care not to overflow when calculating total iov length

Greg KH
2010-12-08T00:59:03Z

From: Jens Axboe <jaxboe@fusionio.com>

commit 9f864c80913467312c7b8690e41fb5ebd1b50e92 upstream.

Reported-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
block/scsi_ioctl.c | 34 ++++++++++++++++++++++++----------
1 file changed, 24 insertions(+), 10 deletions(-)

--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -321,33 +321,47 @@ static int sg_io(struct request_queue *q
if (hdr->iovec_count) {
const int size = sizeof(struct sg_iovec) * hdr->iovec_count;
size_t iov_data_len;
- struct sg_iovec *iov;
+ struct sg_iovec *sg_iov;
+ struct iovec *iov;
+ int i;

- iov = kmalloc(size, GFP_KERNEL);
- if (!iov) {
+ sg_iov = kmalloc(size, GFP_KERNEL);
+ if (!sg_iov) {
ret = -ENOMEM;
goto out;
}

- if (copy_from_user(iov, hdr->dxferp, size)) {
- kfree(iov);
+ if (copy_from_user(sg_iov, hdr->dxferp, size)) {
+ kfree(sg_iov);
ret = -EFAULT;
goto out;
}

+ /*
+ * Sum up the vecs, making sure they don't overflow
+ */
+ iov = (struct iovec *) sg_iov;
+ iov_data_len = 0;
+ for (i = 0; i < hdr->iovec_count; i++) {
+ if (iov_data_len + iov[i].iov_len < iov_data_len) {
+ kfree(sg_iov);
+ ret = -EINVAL;
+ goto out;
+ }
+ iov_data_len += iov[i].iov_len;
+ }
+
/* SG_IO howto says that the shorter of the two wins */
- iov_data_len = iov_length((struct iovec *)iov,
- hdr->iovec_count);
if (hdr->dxfer_len < iov_data_len) {
- hdr->iovec_count = iov_shorten((struct iovec *)iov,
+ hdr->iovec_count = iov_shorten(iov,
hdr->iovec_count,
hdr->dxfer_len);
iov_data_len = hdr->dxfer_len;
}

- ret = blk_rq_map_user_iov(q, rq, NULL, iov, hdr->iovec_count,
+ ret = blk_rq_map_user_iov(q, rq, NULL, sg_iov, hdr->iovec_count,
iov_data_len, GFP_KERNEL);
- kfree(iov);
+ kfree(sg_iov);
} else if (hdr->dxfer_len)
ret = blk_rq_map_user(q, rq, NULL, hdr->dxferp, hdr->dxfer_len,
GFP_KERNEL);