Compression: Prevent undefined behavior when feeding empty input

&emptyVector[n] triggers undefined behavior because it is an out-of-
bounds access, even if n == 0. emptyVector.data() does not (but may
return nullptr).

1 files changed, 7 insertions, 7 deletions

diff --git a/src/lib/compression/compression.cpp b/src/lib/compression/compression.cpp
index 6057f9408..22ee700b6 100644
--- a/src/lib/compression/compression.cpp
+++ b/src/lib/compression/compression.cpp
@@ -104,8 +104,8 @@ void Stream_Compression::process(secure_vector<byte>& buf, size_t offset, u32bit
    if(m_buffer.size() < buf.size() + offset)
       m_buffer.resize(buf.size() + offset);
 
-   m_stream->next_in(&buf[offset], buf.size() - offset);
-   m_stream->next_out(&m_buffer[offset], m_buffer.size() - offset);
+   m_stream->next_in(buf.data() + offset, buf.size() - offset);
+   m_stream->next_out(m_buffer.data() + offset, m_buffer.size() - offset);
 
    while(true)
       {
@@ -115,7 +115,7 @@ void Stream_Compression::process(secure_vector<byte>& buf, size_t offset, u32bit
          {
          const size_t added = 8 + m_buffer.size();
          m_buffer.resize(m_buffer.size() + added);
-         m_stream->next_out(&m_buffer[m_buffer.size() - added], added);
+         m_stream->next_out(m_buffer.data() + m_buffer.size() - added, added);
          }
       else if(m_stream->avail_in() == 0)
          {
@@ -170,8 +170,8 @@ void Stream_Decompression::process(secure_vector<byte>& buf, size_t offset, u32b
    if(m_buffer.size() < buf.size() + offset)
       m_buffer.resize(buf.size() + offset);
 
-   m_stream->next_in(&buf[offset], buf.size() - offset);
-   m_stream->next_out(&m_buffer[offset], m_buffer.size() - offset);
+   m_stream->next_in(buf.data() + offset, buf.size() - offset);
+   m_stream->next_out(m_buffer.data() + offset, m_buffer.size() - offset);
 
    while(true)
       {
@@ -189,14 +189,14 @@ void Stream_Decompression::process(secure_vector<byte>& buf, size_t offset, u32b
          // More data follows: try to process as a following stream
          const size_t read = (buf.size() - offset) - m_stream->avail_in();
          start();
-         m_stream->next_in(&buf[offset + read], buf.size() - offset - read);
+         m_stream->next_in(buf.data() + offset + read, buf.size() - offset - read);
          }
 
       if(m_stream->avail_out() == 0)
          {
          const size_t added = 8 + m_buffer.size();
          m_buffer.resize(m_buffer.size() + added);
-         m_stream->next_out(&m_buffer[m_buffer.size() - added], added);
+         m_stream->next_out(m_buffer.data() + m_buffer.size() - added, added);
          }
       else if(m_stream->avail_in() == 0)
          {