commit 8d6940814a90166e468cee810820e8fc5b74e89d Author: Alexander Færøy ahf@torproject.org Date: Thu Sep 28 16:46:10 2017 +0200

Better error handling when trying to compress/decompress into empty buffer.

This patch ensures that we return TOR_COMPRESS_BUFFER_FULL in case we have a input bytes left to process, but are out of output buffer or in case we need to finish where the compression implementation might need to write an epilogue.

See: https://bugs.torproject.org/23551 --- changes/bug23551 | 3 +++ src/common/compress.c | 7 +++++++ 2 files changed, 10 insertions(+)

diff --git a/changes/bug23551 b/changes/bug23551 new file mode 100644 index 000000000..2f918bfa3 --- /dev/null +++ b/changes/bug23551 @@ -0,0 +1,3 @@ + o Minor bugfixes (compression): + - Handle a pathological case when decompressing Zstandard data when the + output buffer size is zero. Fixes bug 23551; bugfix on 0.3.1.1-alpha. diff --git a/src/common/compress.c b/src/common/compress.c index 7926faaa6..beeff5fcb 100644 --- a/src/common/compress.c +++ b/src/common/compress.c @@ -546,6 +546,13 @@ tor_compress_process(tor_compress_state_t *state, const size_t out_len_orig = *out_len; tor_compress_output_t rv;

+ if (*out_len == 0 && (*in_len > 0 || finish)) { + // If we still have input data, but no space for output data, we might as + // well return early and let the caller do the reallocation of the out + // variable. + return TOR_COMPRESS_BUFFER_FULL; + } + switch (state->method) { case GZIP_METHOD: case ZLIB_METHOD: