| Message ID | ebb82941a86b4e35c4fcfb1ef5a5cfad7c1fceab.1626255956.git.geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm/bridge: nwl-dsi: Avoid potential multiplication overflow on 32-bit | expand |
diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c index 873995f0a7416e58..6002404ffcb9df08 100644 --- a/drivers/gpu/drm/bridge/nwl-dsi.c +++ b/drivers/gpu/drm/bridge/nwl-dsi.c @@ -196,7 +196,7 @@ static u32 ps2bc(struct nwl_dsi *dsi, unsigned long long ps) u32 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format); return DIV64_U64_ROUND_UP(ps * dsi->mode.clock * bpp, - dsi->lanes * 8 * NSEC_PER_SEC); + dsi->lanes * 8ULL * NSEC_PER_SEC); } /*
As nwl_dsi.lanes is u32, and NSEC_PER_SEC is 1000000000L, the second multiplication in dsi->lanes * 8 * NSEC_PER_SEC will overflow on a 32-bit platform. Fix this by making the constant unsigned long long, forcing 64-bit arithmetic. As iMX8 is arm64, this driver is currently used on 64-bit platforms only, where long is 64-bit, so this cannot happen. But the issue will start to happen when the driver is reused for a 32-bit SoC (e.g. i.MX7ULP), or when code is copied for a new driver. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Fabio Estevam <festevam@gmail.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- Compile-tested only. v2: - Add Reviewed-by, - Add reference to i.MX7ULP. --- drivers/gpu/drm/bridge/nwl-dsi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)