[PATCH 1/1] target: Make sure no zero value in the buffer

[PATCH 1/1] target: Make sure no zero value in the buffer

[Xiaohui Zhang]

From: Zhang Xiaohui <ruc_zhangxiaohui@163.com>

The fix makes sure no zero value in the buffer, by comparing the
strlen() of the original buffer with the size variable.

Signed-off-by: Zhang Xiaohui <ruc_zhangxiaohui@163.com>
---
 drivers/target/target_core_iblock.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index f2bd2e207..b23e92449 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -537,6 +537,8 @@ static ssize_t iblock_set_configfs_dev_params(struct se_device *dev,
 	int ret = 0, token;
 	unsigned long tmp_readonly;
 
+	if (strlen(page) < count)
+		return -EOVERFLOW;
 	opts = kstrdup(page, GFP_KERNEL);
 	if (!opts)
 		return -ENOMEM;
-- 
2.17.1

Re: [PATCH 1/1] target: Make sure no zero value in the buffer

[Bodo Stroesser]

On 03.12.20 12:40, Xiaohui Zhang wrote:
> From: Zhang Xiaohui <ruc_zhangxiaohui@163.com>
> 
> The fix makes sure no zero value in the buffer, by comparing the
> strlen() of the original buffer with the size variable.

What problem do you want to fix here?
I think, presently iblock_set_configfs_dev_params() just ignores input after a possible zero byte, which AFAICS is the usual way to handle such 'abnormal' input.

Of course, strictly taken it is a bug to return 'count' without having processed count bytes. OTOH, iblock_set_configfs_dev_params also silently ignores unknown parameter strings.
If you want to have strict error handling in such sys- or config-FS callbacks, you have to do a lot of work ...

> 
> Signed-off-by: Zhang Xiaohui <ruc_zhangxiaohui@163.com>
> ---
>   drivers/target/target_core_iblock.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
> index f2bd2e207..b23e92449 100644
> --- a/drivers/target/target_core_iblock.c
> +++ b/drivers/target/target_core_iblock.c
> @@ -537,6 +537,8 @@ static ssize_t iblock_set_configfs_dev_params(struct se_device *dev,
>   	int ret = 0, token;
>   	unsigned long tmp_readonly;
>   
> +	if (strlen(page) < count)
> +		return -EOVERFLOW;
>   	opts = kstrdup(page, GFP_KERNEL);
>   	if (!opts)
>   		return -ENOMEM;
>