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| author | Michael Tokarev <mjt@tls.msk.ru> | 2011-03-21 09:34:35 +0100 |
|---|---|---|
| committer | Aurelien Jarno <aurelien@aurel32.net> | 2011-04-10 00:14:51 +0200 |
| commit | 2caa9e9d2e0f356cc244bc41ce1d3e81663f6782 (patch) | |
| tree | 99953fa95056b20126f245eca253aa548c1a4195 | |
| parent | a88df0b9b517b76c1a0052fb1b0fe83080559197 (diff) | |
| download | qemu-2caa9e9d2e0f356cc244bc41ce1d3e81663f6782.tar.gz | |
vnc: tight: Fix crash after 2GB of output
fix 2Gb integer overflow in in VNC tight and zlib encodings
As found by Roland Dreier <roland@purestorage.com> (excellent
catch!), when amount of VNC compressed data produced by zlib
and sent to client exceeds 2Gb, integer overflow occurs because
currently, we calculate amount of data produced at each step by
comparing saved total_out with new total_out, and total_out is
something which grows without bounds. Compare it with previous
avail_out instead of total_out, and leave total_out alone.
The same code is used in vnc-enc-tight.c and vnc-enc-zlib.c,
so fix both cases.
There, there's no actual need to save previous_out value, since
capacity-offset (which is how that value is calculated) stays
the same so it can be recalculated again after call to deflate(),
but whole thing becomes less readable this way.
Reported-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Corentin Chary <corentin.chary@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
| -rw-r--r-- | ui/vnc-enc-tight.c | 5 | ||||
| -rw-r--r-- | ui/vnc-enc-zlib.c | 4 |
2 files changed, 5 insertions, 4 deletions
diff --git a/ui/vnc-enc-tight.c b/ui/vnc-enc-tight.c index 2522936193..87fdf35d3e 100644 --- a/ui/vnc-enc-tight.c +++ b/ui/vnc-enc-tight.c @@ -868,8 +868,8 @@ static int tight_compress_data(VncState *vs, int stream_id, size_t bytes, zstream->avail_in = vs->tight.tight.offset; zstream->next_out = vs->tight.zlib.buffer + vs->tight.zlib.offset; zstream->avail_out = vs->tight.zlib.capacity - vs->tight.zlib.offset; + previous_out = zstream->avail_out; zstream->data_type = Z_BINARY; - previous_out = zstream->total_out; /* start encoding */ if (deflate(zstream, Z_SYNC_FLUSH) != Z_OK) { @@ -878,7 +878,8 @@ static int tight_compress_data(VncState *vs, int stream_id, size_t bytes, } vs->tight.zlib.offset = vs->tight.zlib.capacity - zstream->avail_out; - bytes = zstream->total_out - previous_out; + /* ...how much data has actually been produced by deflate() */ + bytes = previous_out - zstream->avail_out; tight_send_compact_size(vs, bytes); vnc_write(vs, vs->tight.zlib.buffer, bytes); diff --git a/ui/vnc-enc-zlib.c b/ui/vnc-enc-zlib.c index 3c6e6abf94..e32e4cd8a8 100644 --- a/ui/vnc-enc-zlib.c +++ b/ui/vnc-enc-zlib.c @@ -103,8 +103,8 @@ static int vnc_zlib_stop(VncState *vs) zstream->avail_in = vs->zlib.zlib.offset; zstream->next_out = vs->output.buffer + vs->output.offset; zstream->avail_out = vs->output.capacity - vs->output.offset; + previous_out = zstream->avail_out; zstream->data_type = Z_BINARY; - previous_out = zstream->total_out; // start encoding if (deflate(zstream, Z_SYNC_FLUSH) != Z_OK) { @@ -113,7 +113,7 @@ static int vnc_zlib_stop(VncState *vs) } vs->output.offset = vs->output.capacity - zstream->avail_out; - return zstream->total_out - previous_out; + return previous_out - zstream->avail_out; } int vnc_zlib_send_framebuffer_update(VncState *vs, int x, int y, int w, int h) |