[PATCH 3.16 026/127] regmap: fix possible ZERO_SIZE_PTR pointer dereferencing error.

[Greg Kroah-Hartman]

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

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

From: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/base/regmap/regmap.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1646,6 +1646,9 @@ out:
 	} else {
 		void *wval;
 
+		if (!val_count)
+			return -EINVAL;
+
 		wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
 		if (!wval) {
 			dev_err(map->dev, "Error in memory allocation\n");


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