From: Nick Terrell <terrelln@fb.com>
Date: Mon, 12 Oct 2020 21:19:04 +0000 (-0700)
Subject: [cwksp] Return NULL when 0 bytes are requested
X-Git-Tag: v1.4.7~38^2~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6bd6b6f7d3ced4e5b1ef8598cc44508a7f60e29a;p=thirdparty%2Fzstd.git

[cwksp] Return NULL when 0 bytes are requested

This ensures that the buffer is never used.
---

diff --git a/lib/compress/zstd_cwksp.h b/lib/compress/zstd_cwksp.h
index 77b91a9bd..5d07352f7 100644
--- a/lib/compress/zstd_cwksp.h
+++ b/lib/compress/zstd_cwksp.h
@@ -178,6 +178,8 @@ MEM_STATIC size_t ZSTD_cwksp_align(size_t size, size_t const align) {
  * else is though.
  */
 MEM_STATIC size_t ZSTD_cwksp_alloc_size(size_t size) {
+    if (size == 0)
+        return 0;
 #if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
     return size + 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE;
 #else
@@ -228,6 +230,9 @@ MEM_STATIC void* ZSTD_cwksp_reserve_internal(
     ZSTD_cwksp_internal_advance_phase(ws, phase);
     alloc = (BYTE *)ws->allocStart - bytes;
 
+    if (bytes == 0)
+        return NULL;
+
 #if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
     /* over-reserve space */
     alloc = (BYTE *)alloc - 2 * ZSTD_CWKSP_ASAN_REDZONE_SIZE;