From: W. Felix Handte <w@felixhandte.com>
Date: Wed, 19 Apr 2023 15:41:51 +0000 (-0400)
Subject: Allow `ZSTD_selectBlockCompressor()` to Return NULL
X-Git-Tag: v1.5.6^2~162^2~17
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cbf3e263160e0bfc9499f55f34c3759a14c0c1cc;p=thirdparty%2Fzstd.git

Allow `ZSTD_selectBlockCompressor()` to Return NULL

Return an error rather than segfaulting.
---

diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index d6133e70b..c28b43456 100644
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -3280,22 +3280,27 @@ static size_t ZSTD_buildSeqStore(ZSTD_CCtx* zc, const void* src, size_t srcSize)
                 }
 
                 /* Fallback to software matchfinder */
-                {   ZSTD_blockCompressor const blockCompressor = ZSTD_selectBlockCompressor(zc->appliedParams.cParams.strategy,
-                                                                                            zc->appliedParams.useRowMatchFinder,
-                                                                                            dictMode);
+                {   ZSTD_blockCompressor const blockCompressor =
+                        ZSTD_selectBlockCompressor(
+                            zc->appliedParams.cParams.strategy,
+                            zc->appliedParams.useRowMatchFinder,
+                            dictMode);
                     ms->ldmSeqStore = NULL;
                     DEBUGLOG(
                         5,
                         "External sequence producer returned error code %lu. Falling back to internal parser.",
                         (unsigned long)nbExternalSeqs
                     );
+                    RETURN_ERROR_IF(blockCompressor == NULL, parameter_combination_unsupported, "Got NULL block compressor!");
                     lastLLSize = blockCompressor(ms, &zc->seqStore, zc->blockState.nextCBlock->rep, src, srcSize);
             }   }
         } else {   /* not long range mode and no external matchfinder */
-            ZSTD_blockCompressor const blockCompressor = ZSTD_selectBlockCompressor(zc->appliedParams.cParams.strategy,
-                                                                                    zc->appliedParams.useRowMatchFinder,
-                                                                                    dictMode);
+            ZSTD_blockCompressor const blockCompressor = ZSTD_selectBlockCompressor(
+                    zc->appliedParams.cParams.strategy,
+                    zc->appliedParams.useRowMatchFinder,
+                    dictMode);
             ms->ldmSeqStore = NULL;
+            RETURN_ERROR_IF(blockCompressor == NULL, parameter_combination_unsupported, "Got NULL block compressor!");
             lastLLSize = blockCompressor(ms, &zc->seqStore, zc->blockState.nextCBlock->rep, src, srcSize);
         }
         {   const BYTE* const lastLiterals = (const BYTE*)src + srcSize - lastLLSize;
diff --git a/lib/compress/zstd_ldm.c b/lib/compress/zstd_ldm.c
index 3d74ff19e..ec0690ccb 100644
--- a/lib/compress/zstd_ldm.c
+++ b/lib/compress/zstd_ldm.c
@@ -672,6 +672,8 @@ size_t ZSTD_ldm_blockCompress(rawSeqStore_t* rawSeqStore,
     /* Input positions */
     BYTE const* ip = istart;
 
+    RETURN_ERROR_IF(blockCompressor == NULL, parameter_combination_unsupported, "Got NULL block compressor!");
+
     DEBUGLOG(5, "ZSTD_ldm_blockCompress: srcSize=%zu", srcSize);
     /* If using opt parser, use LDMs only as candidates rather than always accepting them */
     if (cParams->strategy >= ZSTD_btopt) {