UBI: Validate data_size

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@nod.at>
Reviewed-by: David Gstir <david@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@canonical.com>

diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index d36134925d31fc91bf8c2cacf0429a7b1e366757..db657f2168d7405fb36a80547d29f976208e57ab 100644 (file)
--- 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