[PATCH 3.4 032/177] regmap: fix possible ZERO_SIZE_PTR pointer dereferencing error.

[lizf]

From: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>

3.4.106-rc1 review patch.  If anyone has any objections, please let me know.

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


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>
[lizf: Backported to 3.4: release mutex before returning EINVAL]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
 drivers/base/regmap/regmap.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index e554542..8e81f85 100644
--- 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;
-- 
1.9.1

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