mtd: Add sanity checks in mtd_write/read_oob()

Unlike what's done in mtd_read/write(), there are no checks to make sure
the parameters passed to mtd_read/write_oob() are consistent, which
forces implementers of ->_read/write_oob() to do it, which in turn leads
to code duplication and possibly errors in the logic.

Do general sanity checks, like ops fields consistency and range checking.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Peter Pan <peterpandong@micron.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 44 insertions, 0 deletions

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index ecb0380158f9..f80e911b8843 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -1100,6 +1100,39 @@ int mtd_panic_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
 }
 EXPORT_SYMBOL_GPL(mtd_panic_write);
 
+static int mtd_check_oob_ops(struct mtd_info *mtd, loff_t offs,
+                             struct mtd_oob_ops *ops)
+{
+        /*
+         * Some users are setting ->datbuf or ->oobbuf to NULL, but are leaving
+         * ->len or ->ooblen uninitialized. Force ->len and ->ooblen to 0 in
+         *  this case.
+         */
+        if (!ops->datbuf)
+                ops->len = 0;
+
+        if (!ops->oobbuf)
+                ops->ooblen = 0;
+
+        if (offs < 0 || offs + ops->len >= mtd->size)
+                return -EINVAL;
+
+        if (ops->ooblen) {
+                u64 maxooblen;
+
+                if (ops->ooboffs >= mtd_oobavail(mtd, ops))
+                        return -EINVAL;
+
+                maxooblen = ((mtd_div_by_ws(mtd->size, mtd) -
+                              mtd_div_by_ws(offs, mtd)) *
+                             mtd_oobavail(mtd, ops)) - ops->ooboffs;
+                if (ops->ooblen > maxooblen)
+                        return -EINVAL;
+        }
+
+        return 0;
+}
+
 int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 {
         int ret_code;
@@ -1107,6 +1140,10 @@ int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
         if (!mtd->_read_oob)
                 return -EOPNOTSUPP;
 
+        ret_code = mtd_check_oob_ops(mtd, from, ops);
+        if (ret_code)
+                return ret_code;
+
         ledtrig_mtd_activity();
         /*
          * In cases where ops->datbuf != NULL, mtd->_read_oob() has semantics
@@ -1126,11 +1163,18 @@ EXPORT_SYMBOL_GPL(mtd_read_oob);
 int mtd_write_oob(struct mtd_info *mtd, loff_t to,
                                 struct mtd_oob_ops *ops)
 {
+        int ret;
+
         ops->retlen = ops->oobretlen = 0;
         if (!mtd->_write_oob)
                 return -EOPNOTSUPP;
         if (!(mtd->flags & MTD_WRITEABLE))
                 return -EROFS;
+
+        ret = mtd_check_oob_ops(mtd, to, ops);
+        if (ret)
+                return ret;
+
         ledtrig_mtd_activity();
         return mtd->_write_oob(mtd, to, ops);
 }