diff options
author | Li Zefan <lizefan@huawei.com> | 2013-04-26 14:58:02 -0400 |
---|---|---|
committer | Tejun Heo <tj@kernel.org> | 2013-04-26 14:58:02 -0400 |
commit | cc20e01cd607282d48f8ea538aba10fa850a4312 (patch) | |
tree | 598ff80edab2c3bb3547dcd109e35ed1291f4454 /kernel/cgroup.c | |
parent | 712317ad97f41e738e1a19aa0a6392a78a84094e (diff) |
cgroup: fix use-after-free when umounting cgroupfs
Try:
# mount -t cgroup xxx /cgroup
# mkdir /cgroup/sub && rmdir /cgroup/sub && umount /cgroup
And you might see this:
ida_remove called for id=1 which is not allocated.
It's because cgroup_kill_sb() is called to destroy root->cgroup_ida
and free cgrp->root before ida_simple_removed() is called. What's
worse is we're accessing cgrp->root while it has been freed.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r-- | kernel/cgroup.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 192d762ec1f4..bd4de465d5a9 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c | |||
@@ -848,9 +848,12 @@ static void cgroup_free_fn(struct work_struct *work) | |||
848 | */ | 848 | */ |
849 | dput(cgrp->parent->dentry); | 849 | dput(cgrp->parent->dentry); |
850 | 850 | ||
851 | ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); | ||
852 | |||
851 | /* | 853 | /* |
852 | * Drop the active superblock reference that we took when we | 854 | * Drop the active superblock reference that we took when we |
853 | * created the cgroup | 855 | * created the cgroup. This will free cgrp->root, if we are |
856 | * holding the last reference to @sb. | ||
854 | */ | 857 | */ |
855 | deactivate_super(cgrp->root->sb); | 858 | deactivate_super(cgrp->root->sb); |
856 | 859 | ||
@@ -862,7 +865,6 @@ static void cgroup_free_fn(struct work_struct *work) | |||
862 | 865 | ||
863 | simple_xattrs_free(&cgrp->xattrs); | 866 | simple_xattrs_free(&cgrp->xattrs); |
864 | 867 | ||
865 | ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); | ||
866 | kfree(rcu_dereference_raw(cgrp->name)); | 868 | kfree(rcu_dereference_raw(cgrp->name)); |
867 | kfree(cgrp); | 869 | kfree(cgrp); |
868 | } | 870 | } |