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| author | Sasha Levin <sasha.levin@oracle.com> | 2014-12-29 09:39:01 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-01-29 17:40:56 -0800 |
| commit | a7033e302dcd38bb4333f46b3fdcd930955e402d (patch) | |
| tree | de4529943f09dd87ca1726c6ec75183da68b9502 | |
| parent | e8eb477e22ab989be52e881fa77a1067f9c1ed9e (diff) | |
| download | lwn-a7033e302dcd38bb4333f46b3fdcd930955e402d.tar.gz lwn-a7033e302dcd38bb4333f46b3fdcd930955e402d.zip | |
KEYS: close race between key lookup and freeing
commit a3a8784454692dd72e5d5d34dcdab17b4420e74c upstream.
When a key is being garbage collected, it's key->user would get put before
the ->destroy() callback is called, where the key is removed from it's
respective tracking structures.
This leaves a key hanging in a semi-invalid state which leaves a window open
for a different task to try an access key->user. An example is
find_keyring_by_name() which would dereference key->user for a key that is
in the process of being garbage collected (where key->user was freed but
->destroy() wasn't called yet - so it's still present in the linked list).
This would cause either a panic, or corrupt memory.
Fixes CVE-2014-9529.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | security/keys/gc.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/security/keys/gc.c b/security/keys/gc.c index d67c97bb1025..797818695c87 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -201,12 +201,12 @@ static noinline void key_gc_unused_keys(struct list_head *keys) if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) atomic_dec(&key->user->nikeys); - key_user_put(key->user); - /* now throw away the key memory */ if (key->type->destroy) key->type->destroy(key); + key_user_put(key->user); + kfree(key->description); #ifdef KEY_DEBUGGING |