Merge pull request #895 from lz4/hugefast

Fix #876

3 files changed, 21 insertions, 6 deletions

diff --git a/lib/lz4.c b/lib/lz4.c
index 6322434..1cd7322 100644
--- a/lib/lz4.c
+++ b/lib/lz4.c
@@ -45,10 +45,16 @@
 #endif
 
 /*
- * ACCELERATION_DEFAULT :
+ * LZ4_ACCELERATION_DEFAULT :
  * Select "acceleration" for LZ4_compress_fast() when parameter value <= 0
  */
-#define ACCELERATION_DEFAULT 1
+#define LZ4_ACCELERATION_DEFAULT 1
+/*
+ * LZ4_ACCELERATION_MAX :
+ * Any "acceleration" value higher than this threshold
+ * get treated as LZ4_ACCELERATION_MAX instead (fix #876)
+ */
+#define LZ4_ACCELERATION_MAX 65537
 
 
 /*-************************************
@@ -1191,7 +1197,8 @@ int LZ4_compress_fast_extState(void* state, const char* source, char* dest, int
 {
     LZ4_stream_t_internal* const ctx = & LZ4_initStream(state, sizeof(LZ4_stream_t)) -> internal_donotuse;
     assert(ctx != NULL);
-    if (acceleration < 1) acceleration = ACCELERATION_DEFAULT;
+    if (acceleration < 1) acceleration = LZ4_ACCELERATION_DEFAULT;
+    if (acceleration > LZ4_ACCELERATION_MAX) acceleration = LZ4_ACCELERATION_MAX;
     if (maxOutputSize >= LZ4_compressBound(inputSize)) {
         if (inputSize < LZ4_64Klimit) {
             return LZ4_compress_generic(ctx, source, dest, inputSize, NULL, 0, notLimited, byU16, noDict, noDictIssue, acceleration);
@@ -1221,7 +1228,8 @@ int LZ4_compress_fast_extState(void* state, const char* source, char* dest, int
 int LZ4_compress_fast_extState_fastReset(void* state, const char* src, char* dst, int srcSize, int dstCapacity, int acceleration)
 {
     LZ4_stream_t_internal* ctx = &((LZ4_stream_t*)state)->internal_donotuse;
-    if (acceleration < 1) acceleration = ACCELERATION_DEFAULT;
+    if (acceleration < 1) acceleration = LZ4_ACCELERATION_DEFAULT;
+    if (acceleration > LZ4_ACCELERATION_MAX) acceleration = LZ4_ACCELERATION_MAX;
 
     if (dstCapacity >= LZ4_compressBound(srcSize)) {
         if (srcSize < LZ4_64Klimit) {
@@ -1498,7 +1506,8 @@ int LZ4_compress_fast_continue (LZ4_stream_t* LZ4_stream,
     DEBUGLOG(5, "LZ4_compress_fast_continue (inputSize=%i)", inputSize);
 
     LZ4_renormDictT(streamPtr, inputSize);   /* avoid index overflow */
-    if (acceleration < 1) acceleration = ACCELERATION_DEFAULT;
+    if (acceleration < 1) acceleration = LZ4_ACCELERATION_DEFAULT;
+    if (acceleration > LZ4_ACCELERATION_MAX) acceleration = LZ4_ACCELERATION_MAX;
 
     /* invalidate tiny dictionaries */
     if ( (streamPtr->dictSize-1 < 4-1)   /* intentional underflow */
diff --git a/lib/lz4.h b/lib/lz4.h
index 9b3d758..6ea7cb3 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -186,7 +186,8 @@ LZ4LIB_API int LZ4_compressBound(int inputSize);
     The larger the acceleration value, the faster the algorithm, but also the lesser the compression.
     It's a trade-off. It can be fine tuned, with each successive value providing roughly +~3% to speed.
     An acceleration value of "1" is the same as regular LZ4_compress_default()
-    Values <= 0 will be replaced by ACCELERATION_DEFAULT (currently == 1, see lz4.c).
+    Values <= 0 will be replaced by LZ4_ACCELERATION_DEFAULT (currently == 1, see lz4.c).
+    Values > LZ4_ACCELERATION_MAX will be replaced by LZ4_ACCELERATION_MAX (currently == 65537, see lz4.c).
 */
 LZ4LIB_API int LZ4_compress_fast (const char* src, char* dst, int srcSize, int dstCapacity, int acceleration);
 
diff --git a/tests/Makefile b/tests/Makefile
index 1f8321c..05cae15 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -152,6 +152,9 @@ DD:=dd
 list:
 	@$(MAKE) -pRrq -f $(lastword $(MAKEFILE_LIST)) : 2>/dev/null | awk -v RS= -F: '/^# File/,/^# Finished Make data base/ {if ($$1 !~ "^[#.]") {print $$1}}' | sort | egrep -v -e '^[^[:alnum:]]' -e '^$@$$' | xargs
 
+.PHONY: check
+check: test-lz4-essentials
+
 .PHONY: test
 test: test-lz4 test-lz4c test-frametest test-fullbench test-fuzzer test-install test-amalgamation listTest
 
@@ -349,6 +352,8 @@ test-lz4-basic: lz4 datagen unlz4 lz4cat
 	test "$(shell ./datagen -g20KB | $(LZ4) -c --fast=1 | wc -c)" -eq "$(shell ./datagen -g20KB| $(LZ4) -c --fast| wc -c)" # checks default fast compression is -1
 	! $(LZ4) -c --fast=0 tmp-tlb-dg20K # lz4 should fail when fast=0
 	! $(LZ4) -c --fast=-1 tmp-tlb-dg20K # lz4 should fail when fast=-1
+	# High --fast values can result in out-of-bound dereferences #876
+	./datagen -g1M | $(LZ4) -c --fast=999999999 > /dev/null
 	# Test for #596
 	@echo "TEST" > tmp-tlb-test
 	$(LZ4) -m tmp-tlb-test