Messages in this thread Patch in this message | | | From | Geert Uytterhoeven <> | Subject | [PATCH v2] drm/bridge: nwl-dsi: Avoid potential multiplication overflow on 32-bit | Date | Wed, 14 Jul 2021 11:48:06 +0200 |
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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(-)
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); } /* -- 2.25.1
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