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>
[lizf: Backported to 3.4: release mutex before returning EINVAL]
Signed-off-by: Zefan Li <lizefan@huawei.com>

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index e5545427b46bc5f0e17c6e0dd36ab015d078159b..8e81f85b1ba008d5d45399e45d37bdf08a0d2616 100644 (file)
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -600,6 +600,11 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
        if (val_bytes == 1) {
                wval = (void *)val;
        } else {
+               if (!val_count) {
+                       ret = -EINVAL;
+                       goto out;
+               }
+
                wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
                if (!wval) {
                        ret = -ENOMEM;