[PATCH 3.13 058/105] regmap: fix possible ZERO_SIZE_PTR pointer dereferencing error.

Kamal Mostafa kamal at canonical.com
Mon Oct 27 18:56:33 UTC 2014 -stable review patch.  If anyone has any objections, please let me know.


From: Xiubo Li <Li.Xiubo at freescale.com>

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

Signed-off-by: Xiubo Li <Li.Xiubo at freescale.com>
Signed-off-by: Mark Brown <broonie at kernel.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/base/regmap/regmap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 1ac3c9a..ebe332c 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1529,6 +1529,9 @@ int regmap_bulk_write(struct regmap *map, unsigned int reg, const void *val,
 	if (val_bytes == 1) {
 		wval = (void *)val;
 	} else {
+		if (!val_count)
+			return -EINVAL;
 		wval = kmemdup(val, val_count * val_bytes, GFP_KERNEL);
 		if (!wval) {
 			ret = -ENOMEM;

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