aboutsummaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorPhil Carmody <ext-phil.2.carmody@nokia.com>2011-03-22 16:30:13 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2011-03-27 11:35:43 -0700
commit9432a739a5063919c14c15c722c653a16d797474 (patch)
tree099464fced9a6e6da3587cee2b8916abe8fe86ec /kernel
parent715335d9edcad02a3502a609290229ce179a62a1 (diff)
downloadlinux-linaro-android-9432a739a5063919c14c15c722c653a16d797474.tar.gz
cgroups: if you list_empty() a head then don't list_del() it
commit 8d2587970b8bdf7c8d9208e3f4bb93182aef1a0f upstream. list_del() leaves poison in the prev and next pointers. The next list_empty() will compare those poisons, and say the list isn't empty. Any list operations that assume the node is on a list because of such a check will be fooled into dereferencing poison. One needs to INIT the node after the del, and fortunately there's already a wrapper for that - list_del_init(). Some of the dels are followed by deallocations, so can be ignored, and one can be merged with an add to make a move. Apart from that, I erred on the side of caution in making nodes list_empty()-queriable. Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c14
1 files changed, 6 insertions, 8 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b24d7027b83..bcc73369ac2 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1813,10 +1813,8 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
/* Update the css_set linked lists if we're using them */
write_lock(&css_set_lock);
- if (!list_empty(&tsk->cg_list)) {
- list_del(&tsk->cg_list);
- list_add(&tsk->cg_list, &newcg->tasks);
- }
+ if (!list_empty(&tsk->cg_list))
+ list_move(&tsk->cg_list, &newcg->tasks);
write_unlock(&css_set_lock);
for_each_subsys(root, ss) {
@@ -3655,12 +3653,12 @@ again:
spin_lock(&release_list_lock);
set_bit(CGRP_REMOVED, &cgrp->flags);
if (!list_empty(&cgrp->release_list))
- list_del(&cgrp->release_list);
+ list_del_init(&cgrp->release_list);
spin_unlock(&release_list_lock);
cgroup_lock_hierarchy(cgrp->root);
/* delete this cgroup from parent->children */
- list_del(&cgrp->sibling);
+ list_del_init(&cgrp->sibling);
cgroup_unlock_hierarchy(cgrp->root);
d = dget(cgrp->dentry);
@@ -3879,7 +3877,7 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
subsys[ss->subsys_id] = NULL;
/* remove subsystem from rootnode's list of subsystems */
- list_del(&ss->sibling);
+ list_del_init(&ss->sibling);
/*
* disentangle the css from all css_sets attached to the dummytop. as
@@ -4253,7 +4251,7 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
if (!list_empty(&tsk->cg_list)) {
write_lock(&css_set_lock);
if (!list_empty(&tsk->cg_list))
- list_del(&tsk->cg_list);
+ list_del_init(&tsk->cg_list);
write_unlock(&css_set_lock);
}