hw/display/exynos4210_fimd: Fix potential NULL pointer dereference

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>

diff --git a/hw/display/exynos4210_fimd.c b/hw/display/exynos4210_fimd.c
index 4c16e1f5a0074a6be5a852e32a8b8481c0552e0c..34a960a976534ac8b960302d42fcd8ce4e175f43 100644 (file)
--- a/hw/display/exynos4210_fimd.c
+++ b/hw/display/exynos4210_fimd.c
@@ -1275,12 +1275,14 @@ 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);