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SubjectRe: [PATCH] staging: media: davinci_vpfe: add error handling on kmalloc failure
On Fri, Mar 16, 2018 at 01:58:23PM +0900, Ji-Hun Kim wrote:
> There is no failure checking on the param value which will be allocated
> memory by kmalloc. Add a null pointer checking statement. Then goto error:
> and return -ENOMEM error code when kmalloc is failed.
>
> Signed-off-by: Ji-Hun Kim <ji_hun.kim@samsung.com>
> ---
> drivers/staging/media/davinci_vpfe/dm365_ipipe.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/staging/media/davinci_vpfe/dm365_ipipe.c b/drivers/staging/media/davinci_vpfe/dm365_ipipe.c
> index 6a3434c..55a922c 100644
> --- a/drivers/staging/media/davinci_vpfe/dm365_ipipe.c
> +++ b/drivers/staging/media/davinci_vpfe/dm365_ipipe.c
> @@ -1280,6 +1280,10 @@ static int ipipe_s_config(struct v4l2_subdev *sd, struct vpfe_ipipe_config *cfg)
>
> params = kmalloc(sizeof(struct ipipe_module_params),
> GFP_KERNEL);
> + if (!params) {
> + rval = -ENOMEM;
> + goto error;
^^^^^^^^^^

What does "goto error" do, do you think? It's not clear from the name.
When you have an unclear goto like this it often means the error
handling is going to be buggy.

In this case, it does nothing so a direct "return -ENOMEM;" would be
more clear. But the rest of the error handling is buggy.

1263 static int ipipe_s_config(struct v4l2_subdev *sd, struct vpfe_ipipe_config *cfg)
1264 {
1265 struct vpfe_ipipe_device *ipipe = v4l2_get_subdevdata(sd);
1266 unsigned int i;
1267 int rval = 0;
1268
1269 for (i = 0; i < ARRAY_SIZE(ipipe_modules); i++) {
1270 unsigned int bit = 1 << i;
1271
1272 if (cfg->flag & bit) {
1273 const struct ipipe_module_if *module_if =
1274 &ipipe_modules[i];
1275 struct ipipe_module_params *params;
1276 void __user *from = *(void * __user *)
1277 ((void *)cfg + module_if->config_offset);
1278 size_t size;
1279 void *to;
1280
1281 params = kmalloc(sizeof(struct ipipe_module_params),
1282 GFP_KERNEL);

Do a direct return:

if (!params)
return -ENOMEM;

1283 to = (void *)params + module_if->param_offset;
1284 size = module_if->param_size;
1285
1286 if (to && from && size) {
1287 if (copy_from_user(to, from, size)) {
1288 rval = -EFAULT;
1289 break;

The most recent thing we allocated is "params" so lets do a
"goto free_params;". We'll have to declare "params" at the start of the
function instead inside this block.

1290 }
1291 rval = module_if->set(ipipe, to);
1292 if (rval)
1293 goto error;

goto free_params again since params is still the most recent thing we
allocated.

1294 } else if (to && !from && size) {
1295 rval = module_if->set(ipipe, NULL);
1296 if (rval)
1297 goto error;

And here again goto free_params.

1298 }
1299 kfree(params);
1300 }
1301 }
1302 error:
1303 return rval;


Change this to:

return 0;

free_params:
kfree(params);
return rval;

1304 }

regards,
dan carpenter

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