ZSTD_createCDict_advanced2() must ensure that
ZSTD_createCDict_advanced_internal() has successfully
allocated cdict.  customMalloc() may be called under
low memory condition and may be unable to allocate
workspace for cdict.

Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
 lib/zstd/compress/zstd_compress.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/zstd/compress/zstd_compress.c b/lib/zstd/compress/zstd_compress.c
index c1c316e9e289..e48c73880477 100644
--- a/lib/zstd/compress/zstd_compress.c
+++ b/lib/zstd/compress/zstd_compress.c
@@ -5336,6 +5336,8 @@ ZSTD_CDict* ZSTD_createCDict_advanced2(
                         dictLoadMethod, cctxParams.cParams,
                         cctxParams.useRowMatchFinder, cctxParams.enableDedicatedDictSearch,
                         customMem);
+    if (!cdict)
+        return NULL;
 
     if (ZSTD_isError( ZSTD_initCDict_internal(cdict,
                                     dict, dictSize,
-- 
2.46.0.469.g59c65b2a67-goog