Re: [Qemu-devel] [PATCH 3/4] lm32: milkymist-tmu2: fix integer overflow

[Peter Maydell]

On 12 October 2016 at 23:35, Michael Walle  wrote:
> Don't truncate the multiplication and do a 64 bit one instead because
> because the result is stored in a 64 bit variable.
>
> Spotted by coverity, CID 1167561.
>
> Signed-off-by: Michael Walle 
> ---
>  hw/display/milkymist-tmu2.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/display/milkymist-tmu2.c b/hw/display/milkymist-tmu2.c
> index 9c00184..5c666f9 100644
> --- a/hw/display/milkymist-tmu2.c
> +++ b/hw/display/milkymist-tmu2.c
> @@ -213,7 +213,7 @@ static void tmu2_start(MilkymistTMU2State *s)
>  /* Read the QEMU source framebuffer into an OpenGL texture */
>  glGenTextures(1, );
>  glBindTexture(GL_TEXTURE_2D, texture);
> -fb_len = 2*s->regs[R_TEXHRES]*s->regs[R_TEXVRES];
> +fb_len = 2ULL * s->regs[R_TEXHRES] * s->regs[R_TEXVRES];
>  fb = cpu_physical_memory_map(s->regs[R_TEXFBUF], _len, 0);
>  if (fb == NULL) {
>  glDeleteTextures(1, );
> --
> 2.1.4
>

Reviewed-by: Peter Maydell 

thanks
-- PMM

[Qemu-devel] [PATCH 3/4] lm32: milkymist-tmu2: fix integer overflow

[Michael Walle]

Don't truncate the multiplication and do a 64 bit one instead because
because the result is stored in a 64 bit variable.

Spotted by coverity, CID 1167561.

Signed-off-by: Michael Walle 
---
 hw/display/milkymist-tmu2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/display/milkymist-tmu2.c b/hw/display/milkymist-tmu2.c
index 9c00184..5c666f9 100644
--- a/hw/display/milkymist-tmu2.c
+++ b/hw/display/milkymist-tmu2.c
@@ -213,7 +213,7 @@ static void tmu2_start(MilkymistTMU2State *s)
 /* Read the QEMU source framebuffer into an OpenGL texture */
 glGenTextures(1, );
 glBindTexture(GL_TEXTURE_2D, texture);
-fb_len = 2*s->regs[R_TEXHRES]*s->regs[R_TEXVRES];
+fb_len = 2ULL * s->regs[R_TEXHRES] * s->regs[R_TEXVRES];
 fb = cpu_physical_memory_map(s->regs[R_TEXFBUF], _len, 0);
 if (fb == NULL) {
 glDeleteTextures(1, );
-- 
2.1.4