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authorAl Viro <viro@zeniv.linux.org.uk>2022-05-18 02:13:40 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2022-05-18 02:20:17 -0400
commita91714312eb16f9ecd1f7f8b3efe1380075f28d4 (patch)
tree05ca2e6cf5a7d10291af1bdf2dc7bd164e85a234 /lib
parentfeb9c5e19e913b53cb536a7aa7c9f20107bb51ec (diff)
percpu_ref_init(): clean ->percpu_count_ref on failure
That way percpu_ref_exit() is safe after failing percpu_ref_init(). At least one user (cgroup_create()) had a double-free that way; there might be other similar bugs. Easier to fix in percpu_ref_init(), rather than playing whack-a-mole in sloppy users... Usual symptoms look like a messed refcounting in one of subsystems that use percpu allocations (might be percpu-refcount, might be something else). Having refcounts for two different objects share memory is Not Nice(tm)... Reported-by: syzbot+5b1e53987f858500ec00@syzkaller.appspotmail.com Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'lib')
-rw-r--r--lib/percpu-refcount.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index af9302141bcf..e5c5315da274 100644
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -76,6 +76,7 @@ int percpu_ref_init(struct percpu_ref *ref, percpu_ref_func_t *release,
data = kzalloc(sizeof(*ref->data), gfp);
if (!data) {
free_percpu((void __percpu *)ref->percpu_count_ptr);
+ ref->percpu_count_ptr = 0;
return -ENOMEM;
}