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From patchwork Thu Oct 1 12:39:26 2015
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Content-Type: text/plain; charset="utf-8"
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MIME-Version: 1.0
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Content-Transfer-Encoding: 7bit
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Subject: [net] inet: fix race in reqsk_queue_unlink()
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From: Eric Dumazet <eric.dumazet@gmail.com>
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X-Patchwork-Id: 524966
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Message-Id: <1443703166.32531.47.camel@edumazet-glaptop2.roam.corp.google.com>
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To: David Miller <davem@davemloft.net>
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Cc: netdev <netdev@vger.kernel.org>, Yuchung Cheng <ycheng@google.com>
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Date: Thu, 01 Oct 2015 05:39:26 -0700
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From: Eric Dumazet <edumazet@google.com>
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reqsk_timer_handler() tests if icsk_accept_queue.listen_opt
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is NULL at its beginning.
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By the time it calls inet_csk_reqsk_queue_drop() and
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reqsk_queue_unlink(), listener might have been closed and
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inet_csk_listen_stop() had called reqsk_queue_yank_acceptq()
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which sets icsk_accept_queue.listen_opt to NULL
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We therefore need to correctly check listen_opt being NULL
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after holding syn_wait_lock for proper synchronization.
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Fixes: fa76ce7328b2 ("inet: get rid of central tcp/dccp listener timer")
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Fixes: b357a364c57c ("inet: fix possible panic in reqsk_queue_unlink()")
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Signed-off-by: Eric Dumazet <edumazet@google.com>
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Cc: Yuchung Cheng <ycheng@google.com>
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---
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net/ipv4/inet_connection_sock.c | 19 ++++++++++---------
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1 file changed, 10 insertions(+), 9 deletions(-)
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--
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To unsubscribe from this list: send the line "unsubscribe netdev" in
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the body of a message to majordomo@vger.kernel.org
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More majordomo info at http://vger.kernel.org/majordomo-info.html
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diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
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index 7bb9c39e0a4d..61b45a17fc73 100644
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--- a/net/ipv4/inet_connection_sock.c
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+++ b/net/ipv4/inet_connection_sock.c
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@@ -577,21 +577,22 @@ EXPORT_SYMBOL(inet_rtx_syn_ack);
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static bool reqsk_queue_unlink(struct request_sock_queue *queue,
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struct request_sock *req)
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{
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- struct listen_sock *lopt = queue->listen_opt;
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struct request_sock **prev;
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+ struct listen_sock *lopt;
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bool found = false;
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spin_lock(&queue->syn_wait_lock);
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-
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- for (prev = &lopt->syn_table[req->rsk_hash]; *prev != NULL;
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- prev = &(*prev)->dl_next) {
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- if (*prev == req) {
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- *prev = req->dl_next;
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- found = true;
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- break;
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+ lopt = queue->listen_opt;
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+ if (lopt) {
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+ for (prev = &lopt->syn_table[req->rsk_hash]; *prev != NULL;
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+ prev = &(*prev)->dl_next) {
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+ if (*prev == req) {
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+ *prev = req->dl_next;
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+ found = true;
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+ break;
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+ }
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}
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}
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-
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spin_unlock(&queue->syn_wait_lock);
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if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
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reqsk_put(req);
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