From b47d7ad29bc7f30d4ea3fdb0ef86942468416b79 Mon Sep 17 00:00:00 2001
From: AlexChen <alex.chen@huawei.com>
Date: Mon, 2 Nov 2020 16:52:17 +0000
Subject: [PATCH] hw/display/exynos4210_fimd: Fix potential NULL pointer
 dereference
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In exynos4210_fimd_update(), the pointer s is dereferinced before
being check if it is valid, which may lead to NULL pointer dereference.
So move the assignment to global_width after checking that the s is valid.

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 5F9F8D88.9030102@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry-picked from commit 18520fa465)
---
 hw/display/exynos4210_fimd.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/display/exynos4210_fimd.c b/hw/display/exynos4210_fimd.c
index 61f7408b1c..85b0ebf23a 100644
--- a/hw/display/exynos4210_fimd.c
+++ b/hw/display/exynos4210_fimd.c
@@ -1271,12 +1271,14 @@ static void exynos4210_fimd_update(void *opaque)
     bool blend = false;
     uint8_t *host_fb_addr;
     bool is_dirty = false;
-    const int global_width = (s->vidtcon[2] & FIMD_VIDTCON2_SIZE_MASK) + 1;
+    int global_width;
 
     if (!s || !s->console || !s->enabled ||
         surface_bits_per_pixel(qemu_console_surface(s->console)) == 0) {
         return;
     }
+
+    global_width = (s->vidtcon[2] & FIMD_VIDTCON2_SIZE_MASK) + 1;
     exynos4210_update_resolution(s);
     surface = qemu_console_surface(s->console);
 
-- 
2.27.0

