From b00df840fb4004b7087940ac5f68801562d0d2de Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 12 Aug 2019 23:30:06 +0100 Subject: rxrpc: Fix local endpoint replacement When a local endpoint (struct rxrpc_local) ceases to be in use by any AF_RXRPC sockets, it starts the process of being destroyed, but this doesn't cause it to be removed from the namespace endpoint list immediately as tearing it down isn't trivial and can't be done in softirq context, so it gets deferred. If a new socket comes along that wants to bind to the same endpoint, a new rxrpc_local object will be allocated and rxrpc_lookup_local() will use list_replace() to substitute the new one for the old. Then, when the dying object gets to rxrpc_local_destroyer(), it is removed unconditionally from whatever list it is on by calling list_del_init(). However, list_replace() doesn't reset the pointers in the replaced list_head and so the list_del_init() will likely corrupt the local endpoints list. Fix this by using list_replace_init() instead. Fixes: 730c5fd42c1e ("rxrpc: Fix local endpoint refcounting") Reported-by: syzbot+193e29e9387ea5837f1d@syzkaller.appspotmail.com Signed-off-by: David Howells --- net/rxrpc/local_object.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net') diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c index c9db3e762d8d..c45765b7263e 100644 --- a/net/rxrpc/local_object.c +++ b/net/rxrpc/local_object.c @@ -283,7 +283,7 @@ struct rxrpc_local *rxrpc_lookup_local(struct net *net, goto sock_error; if (cursor != &rxnet->local_endpoints) - list_replace(cursor, &local->link); + list_replace_init(cursor, &local->link); else list_add_tail(&local->link, cursor); age = "new"; -- cgit v1.2.3-59-g8ed1b From 06d9532fa6b34f12a6d75711162d47c17c1add72 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 13 Aug 2019 22:26:36 +0100 Subject: rxrpc: Fix read-after-free in rxrpc_queue_local() rxrpc_queue_local() attempts to queue the local endpoint it is given and then, if successful, prints a trace line. The trace line includes the current usage count - but we're not allowed to look at the local endpoint at this point as we passed our ref on it to the workqueue. Fix this by reading the usage count before queuing the work item. Also fix the reading of local->debug_id for trace lines, which must be done with the same consideration as reading the usage count. Fixes: 09d2bf595db4 ("rxrpc: Add a tracepoint to track rxrpc_local refcounting") Reported-by: syzbot+78e71c5bab4f76a6a719@syzkaller.appspotmail.com Signed-off-by: David Howells --- include/trace/events/rxrpc.h | 6 +++--- net/rxrpc/local_object.c | 19 ++++++++++--------- 2 files changed, 13 insertions(+), 12 deletions(-) (limited to 'net') diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index cc1d060cbf13..fa06b528c73c 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -498,10 +498,10 @@ rxrpc_tx_points; #define E_(a, b) { a, b } TRACE_EVENT(rxrpc_local, - TP_PROTO(struct rxrpc_local *local, enum rxrpc_local_trace op, + TP_PROTO(unsigned int local_debug_id, enum rxrpc_local_trace op, int usage, const void *where), - TP_ARGS(local, op, usage, where), + TP_ARGS(local_debug_id, op, usage, where), TP_STRUCT__entry( __field(unsigned int, local ) @@ -511,7 +511,7 @@ TRACE_EVENT(rxrpc_local, ), TP_fast_assign( - __entry->local = local->debug_id; + __entry->local = local_debug_id; __entry->op = op; __entry->usage = usage; __entry->where = where; diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c index c45765b7263e..72a6e12a9304 100644 --- a/net/rxrpc/local_object.c +++ b/net/rxrpc/local_object.c @@ -93,7 +93,7 @@ static struct rxrpc_local *rxrpc_alloc_local(struct rxrpc_net *rxnet, local->debug_id = atomic_inc_return(&rxrpc_debug_id); memcpy(&local->srx, srx, sizeof(*srx)); local->srx.srx_service = 0; - trace_rxrpc_local(local, rxrpc_local_new, 1, NULL); + trace_rxrpc_local(local->debug_id, rxrpc_local_new, 1, NULL); } _leave(" = %p", local); @@ -321,7 +321,7 @@ struct rxrpc_local *rxrpc_get_local(struct rxrpc_local *local) int n; n = atomic_inc_return(&local->usage); - trace_rxrpc_local(local, rxrpc_local_got, n, here); + trace_rxrpc_local(local->debug_id, rxrpc_local_got, n, here); return local; } @@ -335,7 +335,8 @@ struct rxrpc_local *rxrpc_get_local_maybe(struct rxrpc_local *local) if (local) { int n = atomic_fetch_add_unless(&local->usage, 1, 0); if (n > 0) - trace_rxrpc_local(local, rxrpc_local_got, n + 1, here); + trace_rxrpc_local(local->debug_id, rxrpc_local_got, + n + 1, here); else local = NULL; } @@ -343,16 +344,16 @@ struct rxrpc_local *rxrpc_get_local_maybe(struct rxrpc_local *local) } /* - * Queue a local endpoint unless it has become unreferenced and pass the - * caller's reference to the work item. + * Queue a local endpoint and pass the caller's reference to the work item. */ void rxrpc_queue_local(struct rxrpc_local *local) { const void *here = __builtin_return_address(0); + unsigned int debug_id = local->debug_id; + int n = atomic_read(&local->usage); if (rxrpc_queue_work(&local->processor)) - trace_rxrpc_local(local, rxrpc_local_queued, - atomic_read(&local->usage), here); + trace_rxrpc_local(debug_id, rxrpc_local_queued, n, here); else rxrpc_put_local(local); } @@ -367,7 +368,7 @@ void rxrpc_put_local(struct rxrpc_local *local) if (local) { n = atomic_dec_return(&local->usage); - trace_rxrpc_local(local, rxrpc_local_put, n, here); + trace_rxrpc_local(local->debug_id, rxrpc_local_put, n, here); if (n == 0) call_rcu(&local->rcu, rxrpc_local_rcu); @@ -456,7 +457,7 @@ static void rxrpc_local_processor(struct work_struct *work) container_of(work, struct rxrpc_local, processor); bool again; - trace_rxrpc_local(local, rxrpc_local_processing, + trace_rxrpc_local(local->debug_id, rxrpc_local_processing, atomic_read(&local->usage), NULL); do { -- cgit v1.2.3-59-g8ed1b