UPSTREAM: nvmem: core: return error for non word aligned access

nvmem providers have restrictions on register strides, so return error
when users attempt to read/write buffers with sizes which are less
than word size.

Without this patch the userspace would continue to try as it does not
get any error from the nvmem core, resulting in a hang or endless loop
in userspace.

Change-Id: Iffb76b5a784a79a008f80281ac64449733b855a6
Reported-by: Ariel D'Alessandro <ariel@vanguardiasur.com.ar>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Finley Xiao <finley.xiao@rock-chips.com>
(cherry pick from 2f9ba5b2f8420e0e5712080dafc773f7dd47c3df)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 6fd4e5a5ef4a495bbd412ee33b931f4fb3a8a24f..9d11d98373128fef3de3406975d8bcc2ca286b9a 100644 (file)
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -70,6 +70,9 @@ static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
        if (pos >= nvmem->size)
                return 0;
 
+       if (count < nvmem->word_size)
+               return -EINVAL;
+
        if (pos + count > nvmem->size)
                count = nvmem->size - pos;
 
@@ -95,6 +98,9 @@ static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
        if (pos >= nvmem->size)
                return 0;
 
+       if (count < nvmem->word_size)
+               return -EINVAL;
+
        if (pos + count > nvmem->size)
                count = nvmem->size - pos;