Re: [PATCH 2/2] fs/sysctl: remove redundant link check in proc_sys_link_fill_cache()

[Danilo Krummrich]

On 2018-02-27 23:59, Kees Cook wrote:

On Tue, Feb 27, 2018 at 2:43 PM, Danilo Krummrich
 wrote:

proc_sys_link_fill_cache() does not need to check whether we're
called for a link - it's already done by scan().

Signed-off-by: Danilo Krummrich 
---
 fs/proc/proc_sysctl.c | 11 +--
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index a0b6c647835e..7e7d9facb842 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -707,17 +707,16 @@ static bool proc_sys_link_fill_cache(struct file 
*file,

struct ctl_table *table)
 {
bool ret = true;
+   int err = 0;
head = sysctl_head_grab(head);

if (IS_ERR(head))
return false;

-   if (S_ISLNK(table->mode)) {
-   /* It is not an error if we can not follow the link 
ignore it */

-   int err = sysctl_follow_link(&head, &table);
-   if (err)
-   goto out;
-   }
+   /* It is not an error if we can not follow the link ignore it 
*/

+   sysctl_follow_link(&head, &table);


Shouldn't this be err = sysctl_follow_link... ? Otherwise I don't see
where err is used.

-Kees


Of course, thanks.

+   if (err)
+   goto out;

ret = proc_sys_fill_cache(file, ctx, head, table);
 out:
--
2.14.1

Re: [PATCH 2/2] fs/sysctl: remove redundant link check in proc_sys_link_fill_cache()

[Kees Cook]

On Tue, Feb 27, 2018 at 2:43 PM, Danilo Krummrich
 wrote:
> proc_sys_link_fill_cache() does not need to check whether we're
> called for a link - it's already done by scan().
>
> Signed-off-by: Danilo Krummrich 
> ---
>  fs/proc/proc_sysctl.c | 11 +--
>  1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index a0b6c647835e..7e7d9facb842 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -707,17 +707,16 @@ static bool proc_sys_link_fill_cache(struct file *file,
> struct ctl_table *table)
>  {
> bool ret = true;
> +   int err = 0;
> head = sysctl_head_grab(head);
>
> if (IS_ERR(head))
> return false;
>
> -   if (S_ISLNK(table->mode)) {
> -   /* It is not an error if we can not follow the link ignore it 
> */
> -   int err = sysctl_follow_link(&head, &table);
> -   if (err)
> -   goto out;
> -   }
> +   /* It is not an error if we can not follow the link ignore it */
> +   sysctl_follow_link(&head, &table);

Shouldn't this be err = sysctl_follow_link... ? Otherwise I don't see
where err is used.

-Kees

> +   if (err)
> +   goto out;
>
> ret = proc_sys_fill_cache(file, ctx, head, table);
>  out:
> --
> 2.14.1
>



-- 
Kees Cook
Pixel Security

[PATCH 2/2] fs/sysctl: remove redundant link check in proc_sys_link_fill_cache()

[Danilo Krummrich]

proc_sys_link_fill_cache() does not need to check whether we're
called for a link - it's already done by scan().

Signed-off-by: Danilo Krummrich 
---
 fs/proc/proc_sysctl.c | 11 +--
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index a0b6c647835e..7e7d9facb842 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -707,17 +707,16 @@ static bool proc_sys_link_fill_cache(struct file *file,
struct ctl_table *table)
 {
bool ret = true;
+   int err = 0;
head = sysctl_head_grab(head);
 
if (IS_ERR(head))
return false;
 
-   if (S_ISLNK(table->mode)) {
-   /* It is not an error if we can not follow the link ignore it */
-   int err = sysctl_follow_link(&head, &table);
-   if (err)
-   goto out;
-   }
+   /* It is not an error if we can not follow the link ignore it */
+   sysctl_follow_link(&head, &table);
+   if (err)
+   goto out;
 
ret = proc_sys_fill_cache(file, ctx, head, table);
 out:
-- 
2.14.1