2008-12-23 03:23:21

by Li Zefan

Subject: [PATCH] cgroups: avoid accessing uninitialized data in failure path

If cgroup_get_rootdir() failed, free_cg_links() will be called
in the failure path, but tmp_cg_links hasn't been initialized
at that time.

I should be blamed to introduce this bug in 2.6.26 merge window.

Signed-off-by: Li Zefan <[email protected]>
---
kernel/cgroup.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 8185a0f..330b7ae 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1024,7 +1024,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
if (ret == -EBUSY) {
mutex_unlock(&cgroup_mutex);
mutex_unlock(&inode->i_mutex);
- goto drop_new_super;
+ goto free_cg_links;
}

/* EBUSY should be the only error here */
@@ -1073,10 +1073,11 @@ static int cgroup_get_sb(struct file_system_type *fs_type,

return simple_set_mnt(mnt, sb);

+ free_cg_links:
+ free_cg_links(&tmp_cg_links);
drop_new_super:
up_write(&sb->s_umount);
deactivate_super(sb);
- free_cg_links(&tmp_cg_links);
return ret;
}

--
1.5.4.rc3

2008-12-23 03:26:35

by Li Zefan

Subject: Re: [PATCH] cgroups: avoid accessing uninitialized data in failure path

Li Zefan wrote:
> If cgroup_get_rootdir() failed, free_cg_links() will be called
> in the failure path, but tmp_cg_links hasn't been initialized
> at that time.
>
> I should be blamed to introduce this bug in 2.6.26 merge window.
>

Sorry, I mean 2.6.27 merge window.

> Signed-off-by: Li Zefan <[email protected]>

2008-12-23 16:28:40

by Serge E. Hallyn

Subject: Re: [PATCH] cgroups: avoid accessing uninitialized data in failure path

Quoting Li Zefan ([email protected]):
> If cgroup_get_rootdir() failed, free_cg_links() will be called
> in the failure path, but tmp_cg_links hasn't been initialized
> at that time.
>
> I should be blamed to introduce this bug in 2.6.26 merge window.
>
> Signed-off-by: Li Zefan <[email protected]>

Certainly looks right.

Acked-by: Serge Hallyn <[email protected]>

> ---
> kernel/cgroup.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 8185a0f..330b7ae 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -1024,7 +1024,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
> if (ret == -EBUSY) {
> mutex_unlock(&cgroup_mutex);
> mutex_unlock(&inode->i_mutex);
> - goto drop_new_super;
> + goto free_cg_links;
> }
>
> /* EBUSY should be the only error here */
> @@ -1073,10 +1073,11 @@ static int cgroup_get_sb(struct file_system_type *fs_type,
>
> return simple_set_mnt(mnt, sb);
>
> + free_cg_links:
> + free_cg_links(&tmp_cg_links);
> drop_new_super:
> up_write(&sb->s_umount);
> deactivate_super(sb);
> - free_cg_links(&tmp_cg_links);
> return ret;
> }
>
> --
> 1.5.4.rc3
>
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