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From 4fcace61801f418786c42487c6b06b693ee87666 Mon Sep 17 00:00:00 2001
From: Romain Vimont <rom1v@videolabs.io>
Date: Mon, 19 Sep 2022 17:17:01 +0200
Subject: [PATCH] vnc: fix possible buffer overflow
Upstream-Status: Inappropriate
RPI-Distro repo forks original vlc and applies patches
to enable raspiberry pi support.
Thanks to 0xMitsurugi [1] from Synacktiv [2] for the bug report and fix.
[1] https://twitter.com/0xMitsurugi
[2] https://www.synacktiv.com/
Fixes #27335
(cherry picked from commit 5eb783fd44ed6298db3e38f7765f21c42e4405f9)
---
modules/access/vnc.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)
--- a/modules/access/vnc.c
+++ b/modules/access/vnc.c
@@ -33,6 +33,7 @@
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
+#include <assert.h>
#include <vlc_common.h>
#include <vlc_plugin.h>
@@ -115,7 +116,7 @@
int i_cancel_state;
rfbClient* p_client;
- int i_framebuffersize;
+ size_t i_framebuffersize;
block_t *p_block;
float f_fps;
@@ -143,11 +144,16 @@
p_sys->es = NULL;
}
- int i_width = p_client->width;
- int i_height = p_client->height;
- int i_depth = p_client->format.bitsPerPixel;
+ assert(!(p_client->width & ~0xffff)); // fits in 16 bits
+ uint16_t i_width = p_client->width;
- switch( i_depth )
+ assert(!(p_client->height & ~0xffff)); // fits in 16 bits
+ uint16_t i_height = p_client->height;
+
+ uint8_t i_bits_per_pixel = p_client->format.bitsPerPixel;
+ assert((i_bits_per_pixel & 0x7) == 0); // multiple of 8
+
+ switch( i_bits_per_pixel )
{
case 8:
i_chroma = VLC_CODEC_RGB8;
@@ -180,7 +186,10 @@
}
/* Set up framebuffer */
- p_sys->i_framebuffersize = i_width * i_height * i_depth / 8;
+ if (mul_overflow(i_width, i_height * (i_bits_per_pixel / 8), &p_sys->i_framebuffersize)) {
+ msg_Err(p_demux, "VNC framebuffersize overflow");
+ return FALSE;
+ }
/* Reuse unsent block */
if ( p_sys->p_block )
@@ -211,7 +220,7 @@
fmt.video.i_frame_rate_base = 1000;
fmt.video.i_frame_rate = 1000 * p_sys->f_fps;
- fmt.video.i_bits_per_pixel = i_depth;
+ fmt.video.i_bits_per_pixel = i_bits_per_pixel;
fmt.video.i_rmask = p_client->format.redMax << p_client->format.redShift;
fmt.video.i_gmask = p_client->format.greenMax << p_client->format.greenShift;
fmt.video.i_bmask = p_client->format.blueMax << p_client->format.blueShift;
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