From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Wed, 27 Jan 2021 18:29:11 +0000 (+0200)
Subject: lib-compression: Fix potential hangs with non-blocking istreams
X-Git-Tag: 2.3.15~143
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9a1eba3f4164581fcca9a5d27260261add7edbc7;p=thirdparty%2Fdovecot%2Fcore.git

lib-compression: Fix potential hangs with non-blocking istreams
---

diff --git a/src/lib-compression/istream-lz4.c b/src/lib-compression/istream-lz4.c
index 788c1cc8bf..8638979a6e 100644
--- a/src/lib-compression/istream-lz4.c
+++ b/src/lib-compression/istream-lz4.c
@@ -177,6 +177,11 @@ static ssize_t i_stream_lz4_read(struct istream_private *stream)
 	/* if we already have max_buffer_size amount of data, fail here */
 	if (stream->pos - stream->skip >= i_stream_get_max_buffer_size(&stream->istream))
 		return -2;
+	if (i_stream_get_data_size(zstream->istream.parent) > 0) {
+		/* Parent stream was only partially consumed. Set the stream's
+		   IO as pending to avoid hangs. */
+		i_stream_set_input_pending(&zstream->istream.istream, TRUE);
+	}
 	/* allocate enough space for the old data and the new
 	   decompressed chunk. we don't know the original compressed size,
 	   so just allocate the max amount of memory. */
diff --git a/src/lib-compression/istream-lzma.c b/src/lib-compression/istream-lzma.c
index 126b7aa12c..7b0c2a6a84 100644
--- a/src/lib-compression/istream-lzma.c
+++ b/src/lib-compression/istream-lzma.c
@@ -147,7 +147,14 @@ static ssize_t i_stream_lzma_read(struct istream_private *stream)
 	out_size -= zstream->strm.avail_out;
 	stream->pos += out_size;
 
-	i_stream_skip(stream->parent, size - zstream->strm.avail_in);
+	size_t bytes_consumed = size - zstream->strm.avail_in;
+	i_stream_skip(stream->parent, bytes_consumed);
+	if (i_stream_get_data_size(stream->parent) > 0 &&
+	    (bytes_consumed > 0 || out_size > 0)) {
+		/* Parent stream was only partially consumed. Set the stream's
+		   IO as pending to avoid hangs. */
+		i_stream_set_input_pending(&stream->istream, TRUE);
+	}
 
 	if (lzma_handle_error(zstream, ret) < 0) {
 		return -1;
diff --git a/src/lib-compression/istream-zlib.c b/src/lib-compression/istream-zlib.c
index 777289eb29..a3105a2bde 100644
--- a/src/lib-compression/istream-zlib.c
+++ b/src/lib-compression/istream-zlib.c
@@ -260,7 +260,14 @@ static ssize_t i_stream_zlib_read(struct istream_private *stream)
 					 out_size);
 	stream->pos += out_size;
 
-	i_stream_skip(stream->parent, size - zstream->zs.avail_in);
+	size_t bytes_consumed = size - zstream->zs.avail_in;
+	i_stream_skip(stream->parent, bytes_consumed);
+	if (i_stream_get_data_size(stream->parent) > 0 &&
+	    (bytes_consumed > 0 || out_size > 0)) {
+		/* Parent stream was only partially consumed. Set the stream's
+		   IO as pending to avoid hangs. */
+		i_stream_set_input_pending(&stream->istream, TRUE);
+	}
 
 	switch (ret) {
 	case Z_OK:
diff --git a/src/lib-compression/istream-zstd.c b/src/lib-compression/istream-zstd.c
index 57fb796c8b..9c9ca4f865 100644
--- a/src/lib-compression/istream-zstd.c
+++ b/src/lib-compression/istream-zstd.c
@@ -157,6 +157,10 @@ static ssize_t i_stream_zstd_read(struct istream_private *stream)
 			if (ret == 0)
 				return 0;
 			buffer_append(zstream->frame_buffer, data, size);
+			/* NOTE: All of the parent stream input is skipped
+			   over here. This is why there's no need to call
+			   i_stream_set_input_pending() here like with other
+			   compression istreams. */
 			i_stream_skip(stream->parent, size);
 			zstream->input.src = zstream->frame_buffer->data;
 			zstream->input.size = zstream->frame_buffer->used;