ddidderr/zstd-rs
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[lib] Fix NULL pointer dereference

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When the output buffer is `NULL` with size 0, but the frame content size
is non-zero, we will write to the NULL pointer because our bounds check
underflowed.

This was exposed by a recent PR that allowed an empty frame into the
single-pass shortcut in streaming mode.

* Fix the bug.
* Fix another NULL dereference in zstd-v1.
* Overflow checks in 32-bit mode.
* Add a dedicated test.
* Expose the bug in the dedicated simple_decompress fuzzer.
* Switch all mallocs in fuzzers to return NULL for size=0.
* Fix a new timeout in a fuzzer.

Neither clang nor gcc show a decompression speed regression on x86-64.
On x86-32 clang is slightly positive and gcc loses 2.5% of speed.

Credit to OSS-Fuzz.
This commit is contained in:
Nick Terrell
2020-05-06 12:09:02 -07:00
committed by Nick Terrell
parent ad8dbae1b7
commit 5717bd39ee
26 changed files with 167 additions and 80 deletions
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tests/fuzz/Makefile
+1 -1
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@@ -42,7 +42,7 @@ FUZZ_ARFLAGS := $(ARFLAGS)
FUZZ_TARGET_FLAGS = $(FUZZ_CPPFLAGS) $(FUZZ_CXXFLAGS) $(FUZZ_LDFLAGS)
FUZZ_HEADERS := fuzz_helpers.h fuzz.h zstd_helpers.h fuzz_data_producer.h
FUZZ_SRC := $(PRGDIR)/util.c zstd_helpers.c fuzz_data_producer.c
FUZZ_SRC := $(PRGDIR)/util.c fuzz_helpers.c zstd_helpers.c fuzz_data_producer.c
ZSTDCOMMON_SRC := $(ZSTDDIR)/common/*.c
ZSTDCOMP_SRC := $(ZSTDDIR)/compress/*.c