proc_sys_link_fill_cache() does not take currently unregistering
sysctl tables into account, which might result into a page fault in
sysctl_follow_link() - add a check to fix it.
Signed-off-by: Danilo Krummrich <[email protected]>
---
v2: removed empty line between between sysctl_head_grab and IS_ERR
---
fs/proc/proc_sysctl.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index c5cbbdff3c3d..82ac5f682b73 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -707,7 +707,10 @@ static bool proc_sys_link_fill_cache(struct file *file,
struct ctl_table *table)
{
bool ret = true;
+
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 */
--
2.14.1
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 <[email protected]>
---
v2: removed 'err' as it's only used for sysctl_follow_link()
---
fs/proc/proc_sysctl.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 82ac5f682b73..d36ef667c0a8 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -712,12 +712,9 @@ static bool proc_sys_link_fill_cache(struct file *file,
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 */
+ if (sysctl_follow_link(&head, &table))
+ goto out;
ret = proc_sys_fill_cache(file, ctx, head, table);
out:
--
2.14.1
On Tue, Feb 27, 2018 at 3:31 PM, Danilo Krummrich
<[email protected]> wrote:
> proc_sys_link_fill_cache() does not take currently unregistering
> sysctl tables into account, which might result into a page fault in
> sysctl_follow_link() - add a check to fix it.
>
> Signed-off-by: Danilo Krummrich <[email protected]>
Acked-by: Kees Cook <[email protected]>
> ---
> v2: removed empty line between between sysctl_head_grab and IS_ERR
Thanks!
-Kees
> ---
> fs/proc/proc_sysctl.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index c5cbbdff3c3d..82ac5f682b73 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -707,7 +707,10 @@ static bool proc_sys_link_fill_cache(struct file *file,
> struct ctl_table *table)
> {
> bool ret = true;
> +
> 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 */
> --
> 2.14.1
>
--
Kees Cook
Pixel Security
On Tue, Feb 27, 2018 at 3:31 PM, Danilo Krummrich
<[email protected]> 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 <[email protected]>
Acked-by: Kees Cook <[email protected]>
> ---
> v2: removed 'err' as it's only used for sysctl_follow_link()
Thanks :)
Luis, do you have a tree for sysctl, or should these just go via -mm?
-Kees
> ---
> fs/proc/proc_sysctl.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index 82ac5f682b73..d36ef667c0a8 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -712,12 +712,9 @@ static bool proc_sys_link_fill_cache(struct file *file,
> 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 */
> + if (sysctl_follow_link(&head, &table))
> + goto out;
>
> ret = proc_sys_fill_cache(file, ctx, head, table);
> out:
> --
> 2.14.1
>
--
Kees Cook
Pixel Security
On Wed, Feb 28, 2018 at 12:31:55AM +0100, Danilo Krummrich wrote:
> proc_sys_link_fill_cache() does not take currently unregistering
> sysctl tables into account, which might result into a page fault in
> sysctl_follow_link() - add a check to fix it.
>
> Signed-off-by: Danilo Krummrich <[email protected]>
> ---
> v2: removed empty line between between sysctl_head_grab and IS_ERR
Please add a respective tag:
Fixes: 0e47c99d7fe25 ("sysctl: Replace root_list with links between sysctl_table_sets")
And mention this has been present since v3.4. May be worth sending to
stable as well, so peg stable as well.
Luis
> ---
> fs/proc/proc_sysctl.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
> index c5cbbdff3c3d..82ac5f682b73 100644
> --- a/fs/proc/proc_sysctl.c
> +++ b/fs/proc/proc_sysctl.c
> @@ -707,7 +707,10 @@ static bool proc_sys_link_fill_cache(struct file *file,
> struct ctl_table *table)
> {
> bool ret = true;
> +
> 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 */
> --
> 2.14.1
>
>
--
Luis Rodriguez, SUSE LINUX GmbH
Maxfeldstrasse 5; D-90409 Nuernberg
On Tue, Feb 27, 2018 at 03:41:40PM -0800, Kees Cook wrote:
> On Tue, Feb 27, 2018 at 3:31 PM, Danilo Krummrich
> <[email protected]> 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 <[email protected]>
>
> Acked-by: Kees Cook <[email protected]>
>
> > ---
> > v2: removed 'err' as it's only used for sysctl_follow_link()
>
> Thanks :)
>
> Luis, do you have a tree for sysctl, or should these just go via -mm?
-mm has been working beautifully so far.
Now that acks have been collected, Danilo, can you also add the other tags
mentioned and resubmit and add [email protected] ?
Luis