[PATCH] device-dax: fix 'passing zero to ERR_PTR()' warning

From: Dan Williams
Date: Wed Jul 12 2017 - 17:05:09 EST


Dan Carpenter reports:

The patch 7b6be8444e0f: "dax: refactor dax-fs into a generic provider
of 'struct dax_device' instances" from Apr 11, 2017, leads to the
following static checker warning:

drivers/dax/device.c:643 devm_create_dev_dax()
warn: passing zero to 'ERR_PTR'

Fix the case where we inadvertently leak 0 to ERR_PTR() by setting at
every error case, and make it clear that 'count' is never 0.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/dax/device.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 12943d19bfc4..44d72e5e64cc 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -567,7 +567,10 @@ struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
struct inode *inode;
struct device *dev;
struct cdev *cdev;
- int rc = 0, i;
+ int rc, i;
+
+ if (!count)
+ return ERR_PTR(-EINVAL);

dev_dax = kzalloc(sizeof(*dev_dax) + sizeof(*res) * count, GFP_KERNEL);
if (!dev_dax)
@@ -598,8 +601,10 @@ struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
* device outside of mmap of the resulting character device.
*/
dax_dev = alloc_dax(dev_dax, NULL, NULL);
- if (!dax_dev)
+ if (!dax_dev) {
+ rc = -ENOMEM;
goto err_dax;
+ }

/* from here on we're committed to teardown via dax_dev_release() */
dev = &dev_dax->dev;