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authorDavid Howells <dhowells@redhat.com>2019-08-13 22:26:36 +0100
committerDavid Howells <dhowells@redhat.com>2019-08-14 11:37:51 +0100
commit06d9532fa6b34f12a6d75711162d47c17c1add72 (patch)
tree769d038231f7e58df65b0a3332d5bfcd3fbbf82c /net/rxrpc
parentb00df840fb4004b7087940ac5f68801562d0d2de (diff)
downloadlinux-stericsson-06d9532fa6b34f12a6d75711162d47c17c1add72.tar.gz
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 <dhowells@redhat.com>
Diffstat (limited to 'net/rxrpc')
-rw-r--r--net/rxrpc/local_object.c19
1 files changed, 10 insertions, 9 deletions
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 {