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| author | Eric Biggers <ebiggers@google.com> | 2017-10-09 12:40:00 -0700 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2017-10-12 17:16:40 +0100 |
| commit | d124b2c53c7bee6569d2a2d0b18b4a1afde00134 (patch) | |
| tree | bf9b812982023ef6893d58c1a8bdc8f52bd173fc /fs | |
| parent | 13923d0865ca96312197962522e88bc0aedccd74 (diff) | |
| download | linux-d124b2c53c7bee6569d2a2d0b18b4a1afde00134.tar.gz linux-d124b2c53c7bee6569d2a2d0b18b4a1afde00134.tar.bz2 linux-d124b2c53c7bee6569d2a2d0b18b4a1afde00134.zip | |
FS-Cache: fix dereference of NULL user_key_payload
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>
Cc: <stable@vger.kernel.org> [v2.6.32+]
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs')
| -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 b5ab06fabc60..0438d4cd91ef 100644 --- a/fs/fscache/object-list.c +++ b/fs/fscache/object-list.c @@ -331,6 +331,13 @@ static void fscache_objlist_config(struct fscache_objlist_data *data) rcu_read_lock(); confkey = user_key_payload_rcu(key); + if (!confkey) { + /* key was revoked */ + rcu_read_unlock(); + key_put(key); + goto no_config; + } + buf = confkey-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--) { |