From 7e0668d1e4f78a0c7ff8689b197e2c104ce569e4 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Mon, 23 Nov 2015 11:11:59 +0100
Subject: [SERVER] Fix race condition potentially leading to use after release

---
 src/server/altservers.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'src/server/altservers.c')

diff --git a/src/server/altservers.c b/src/server/altservers.c
index 8eb07ec..7a2aaf7 100644
--- a/src/server/altservers.c
+++ b/src/server/altservers.c
@@ -379,9 +379,9 @@ static void *altservers_main(void *data UNUSED)
 		}
 		// Work your way through the queue
 		for (itLink = 0; itLink < SERVER_MAX_PENDING_ALT_CHECKS; ++itLink) {
-			dnbd3_connection_t * const uplink = pending[itLink];
-			if ( uplink == NULL ) continue; // Check once before locking, as a mutex is expensive
+			if ( pending[itLink] == NULL ) continue; // Check once before locking, as a mutex is expensive
 			pthread_mutex_lock( &pendingLockConsume );
+			dnbd3_connection_t * const uplink = pending[itLink];
 			if ( uplink == NULL ) { // Check again after locking
 				pthread_mutex_unlock( &pendingLockConsume );
 				continue;
-- 
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