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| author | Al Viro <viro@zeniv.linux.org.uk> | 2022-05-18 02:13:40 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2022-05-18 02:20:17 -0400 |
| commit | a91714312eb16f9ecd1f7f8b3efe1380075f28d4 (patch) | |
| tree | 05ca2e6cf5a7d10291af1bdf2dc7bd164e85a234 | |
| parent | feb9c5e19e913b53cb536a7aa7c9f20107bb51ec (diff) | |
| download | linux-a91714312eb16f9ecd1f7f8b3efe1380075f28d4.tar.bz2 | |
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>
| -rw-r--r-- | lib/percpu-refcount.c | 1 |
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; } |