From 2caa9e9d2e0f356cc244bc41ce1d3e81663f6782 Mon Sep 17 00:00:00 2001 From: Michael Tokarev Date: Mon, 21 Mar 2011 09:34:35 +0100 Subject: vnc: tight: Fix crash after 2GB of output fix 2Gb integer overflow in in VNC tight and zlib encodings As found by Roland Dreier (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 Signed-off-by: Michael Tokarev Signed-off-by: Corentin Chary Signed-off-by: Aurelien Jarno --- ui/vnc-enc-zlib.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'ui/vnc-enc-zlib.c') 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) -- cgit v1.2.1