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| author | David Howells <dhowells@redhat.com> | 2019-08-09 15:20:41 +0100 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2019-08-09 15:21:19 +0100 |
| commit | 730c5fd42c1e3652a065448fd235cb9fafb2bd10 (patch) | |
| tree | 60585660be245d94c51a42f4bfa25e488299aca0 /net/rxrpc/ar-internal.h | |
| parent | 8c25d0887a8bd0e1ca2074ac0c6dff173787a83b (diff) | |
| download | linux-730c5fd42c1e3652a065448fd235cb9fafb2bd10.tar.bz2 | |
rxrpc: Fix local endpoint refcounting
The object lifetime management on the rxrpc_local struct is broken in that
the rxrpc_local_processor() function is expected to clean up and remove an
object - but it may get requeued by packets coming in on the backing UDP
socket once it starts running.
This may result in the assertion in rxrpc_local_rcu() firing because the
memory has been scheduled for RCU destruction whilst still queued:
rxrpc: Assertion failed
------------[ cut here ]------------
kernel BUG at net/rxrpc/local_object.c:468!
Note that if the processor comes around before the RCU free function, it
will just do nothing because ->dead is true.
Fix this by adding a separate refcount to count active users of the
endpoint that causes the endpoint to be destroyed when it reaches 0.
The original refcount can then be used to refcount objects through the work
processor and cause the memory to be rcu freed when that reaches 0.
Fixes: 4f95dd78a77e ("rxrpc: Rework local endpoint management")
Reported-by: syzbot+1e0edc4b8b7494c28450@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'net/rxrpc/ar-internal.h')
| -rw-r--r-- | net/rxrpc/ar-internal.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 822f45386e31..9796c45d2f6a 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -254,7 +254,8 @@ struct rxrpc_security { */ struct rxrpc_local { struct rcu_head rcu; - atomic_t usage; + atomic_t active_users; /* Number of users of the local endpoint */ + atomic_t usage; /* Number of references to the structure */ struct rxrpc_net *rxnet; /* The network ns in which this resides */ struct list_head link; struct socket *socket; /* my UDP socket */ @@ -1002,6 +1003,8 @@ struct rxrpc_local *rxrpc_lookup_local(struct net *, const struct sockaddr_rxrpc struct rxrpc_local *rxrpc_get_local(struct rxrpc_local *); struct rxrpc_local *rxrpc_get_local_maybe(struct rxrpc_local *); void rxrpc_put_local(struct rxrpc_local *); +struct rxrpc_local *rxrpc_use_local(struct rxrpc_local *); +void rxrpc_unuse_local(struct rxrpc_local *); void rxrpc_queue_local(struct rxrpc_local *); void rxrpc_destroy_all_locals(struct rxrpc_net *); |