[PATCH] nvmem: core: add sanity check in nvmem_device_read()

[Bingbu Cao]

nvmem_device_read() could be called directly once nvmem device
registered, the sanity check should be done before call
nvmem_reg_read() as cell and sysfs read did now.

Signed-off-by: Bingbu Cao <bingbu.cao@xxxxxxxxx>
---
 drivers/nvmem/core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 927eb5f6003f..c9a77993f008 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1491,6 +1491,13 @@ int nvmem_device_read(struct nvmem_device *nvmem,
 	if (!nvmem)
 		return -EINVAL;
 
+	if (offset >= nvmem->size || bytes < nvmem->word_size)
+		return 0;
+
+	if (bytes + offset > nvmem->size)
+		bytes = nvmem->size - offset;
+
+	bytes = round_down(bytes, nvmem->word_size);
 	rc = nvmem_reg_read(nvmem, offset, buf, bytes);
 
 	if (rc)
-- 
2.7.4