lib: zstd: fix null-deref in ZSTD_createCDict_advanced2()

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.

Link: https://lkml.kernel.org/r/20240902105656.1383858-4-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/zstd/compress/zstd_compress.c b/lib/zstd/compress/zstd_compress.c
index f620cafca633ba691d364efdce0ac33b7a88957e..16bb995bc6c4c03f7c588d849641ac6a89c463fc 100644 (file)
--- a/lib/zstd/compress/zstd_compress.c
+++ b/lib/zstd/compress/zstd_compress.c
@@ -4810,6 +4810,8 @@ 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,