[PATCH 3.16.y-ckt 070/104] UBI: Validate data_size

[Luis Henriques]

3.16.7-ckt19 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Weinberger <richard at nod.at>

commit 281fda27673f833a01d516658a64d22a32c8e072 upstream.

Make sure that data_size is less than LEB size.
Otherwise a handcrafted UBI image is able to trigger
an out of bounds memory access in ubi_compare_lebs().

Signed-off-by: Richard Weinberger <richard at nod.at>
Reviewed-by: David Gstir <david at sigma-star.at>
[ luis: backported to 3.16:
  - no ubi_device parameter for the ubi_err() macro in 3.16 ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/mtd/ubi/io.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index d36134925d31..db657f2168d7 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -921,6 +921,11 @@ static int validate_vid_hdr(const struct ubi_device *ubi,
 		goto bad;
 	}
 
+	if (data_size > ubi->leb_size) {
+		ubi_err("bad data_size");
+		goto bad;
+	}
+
 	if (vol_type == UBI_VID_STATIC) {
 		/*
 		 * Although from high-level point of view static volumes may