regmap: fix possible ZERO_SIZE_PTR pointer dereferencing error.

commit d6b41cb06044a7d895db82bdd54f6e4219970510 upstream.

Since we cannot make sure the 'val_count' will always be none zero
here, and then if it equals to zero, the kmemdup() will return
ZERO_SIZE_PTR, which equals to ((void *)16).

So this patch fix this with just doing the zero check before calling
kmemdup().

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 5277f9a..f6cff3b 100644 (file)
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1557,6 +1557,9 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
        } else {
                void *wval;
 
+               if (!val_count)
+                       return -EINVAL;
+
                wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
                if (!wval) {
                        ret = -ENOMEM;