[Qemu-stable] [PATCH 30/37] page_cache: fix memory leak

[Michael Roth]

From: Peter Lieven <address@hidden>

XBZRLE encoded migration introduced a MRU page cache
meachnism. Unfortunately, cached items where never freed in
case of a collision in the page cache on cache_insert().

This lead to out of memory conditions during XBZRLE migration
if the page cache was small and there where a lot of collisions
in the cache.

Signed-off-by: Peter Lieven <address@hidden>
Signed-off-by: Orit Wasserman <address@hidden>

Reviewed-by: Peter Maydell <address@hidden>
Signed-off-by: Juan Quintela <address@hidden>
(cherry picked from commit 32a1c08b60a8ac0e63b54a5793a26b5e32b36618)

Signed-off-by: Michael Roth <address@hidden>
---
 page_cache.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/page_cache.c b/page_cache.c
index 748957b..b92482c 100644
--- a/page_cache.c
+++ b/page_cache.c
@@ -152,6 +152,9 @@ void cache_insert(PageCache *cache, uint64_t addr, uint8_t 
*pdata)
     /* actual update of entry */
     it = cache_get_by_addr(cache, addr);
 
+    /* free old cached data if any */
+    g_free(it->it_data);
+
     if (!it->it_data) {
         cache->num_items++;
     }
-- 
1.7.9.5