diff options
| author | Eric Biggers <ebiggers@google.com> | 2017-10-09 12:40:00 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-10-27 10:38:11 +0200 |
| commit | d2d576e28554e8d139038ebea27d24503598c97b (patch) | |
| tree | d9a390a8d4c2914276424273f46ddfd529c04708 | |
| parent | 63c8e452554962f88c0952212c8a4202469d4914 (diff) | |
FS-Cache: fix dereference of NULL user_key_payload
commit d124b2c53c7bee6569d2a2d0b18b4a1afde00134 upstream.
When the file /proc/fs/fscache/objects (available with
CONFIG_FSCACHE_OBJECT_LIST=y) is opened, we request a user key with
description "fscache:objlist", then access its payload. However, a
revoked key has a NULL payload, and we failed to check for this.
request_key() *does* skip revoked keys, but there is still a window
where the key can be revoked before we access its payload.
Fix it by checking for a NULL payload, treating it like a key which was
already revoked at the time it was requested.
Fixes: 4fbf4291aa15 ("FS-Cache: Allow the current state of all objects to be dumped")
Reviewed-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/fscache/object-list.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/fscache/object-list.c b/fs/fscache/object-list.c index 5d5ddaa84b21..37e0c31d284f 100644 --- a/fs/fscache/object-list.c +++ b/fs/fscache/object-list.c @@ -330,6 +330,13 @@ static void fscache_objlist_config(struct fscache_objlist_data *data) rcu_read_lock(); confkey = user_key_payload(key); + if (!confkey) { + /* key was revoked */ + rcu_read_unlock(); + key_put(key); + goto no_config; + } + buf = confkey->data; for (len = confkey->datalen - 1; len >= 0; len--) { |