Messages in this thread | | | Date | Thu, 2 May 2024 09:26:56 +0200 | From | Neil Armstrong <> | Subject | Re: [PATCH v3 2/9] drm/mipi-dsi: Fix theoretical int overflow in mipi_dsi_generic_write_seq() |
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On 01/05/2024 17:41, Douglas Anderson wrote: > The mipi_dsi_generic_write_seq() macro makes a call to > mipi_dsi_generic_write() which returns a type ssize_t. The macro then > stores it in an int and checks to see if it's negative. This could > theoretically be a problem if "ssize_t" is larger than "int". > > To see the issue, imagine that "ssize_t" is 32-bits and "int" is > 16-bits, you could see a problem if there was some code out there that > looked like: > > mipi_dsi_generic_write_seq(dsi, <32768 bytes as arguments>); > > ...since we'd get back that 32768 bytes were transferred and 32768 > stored in a 16-bit int would look negative. > > Though there are no callsites where we'd actually hit this (even if > "int" was only 16-bit), it's cleaner to make the types match so let's > fix it. > > Fixes: a9015ce59320 ("drm/mipi-dsi: Add a mipi_dsi_dcs_write_seq() macro") > Signed-off-by: Douglas Anderson <dianders@chromium.org> > --- > > Changes in v3: > - Use %zd in print instead of casting errors to int. > > Changes in v2: > - New > > include/drm/drm_mipi_dsi.h | 22 +++++++++++----------- > 1 file changed, 11 insertions(+), 11 deletions(-) > > diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h > index 70ce0b8cbc68..e0f56564bf97 100644 > --- a/include/drm/drm_mipi_dsi.h > +++ b/include/drm/drm_mipi_dsi.h > @@ -314,17 +314,17 @@ int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi, > * @dsi: DSI peripheral device > * @seq: buffer containing the payload > */ > -#define mipi_dsi_generic_write_seq(dsi, seq...) \ > - do { \ > - static const u8 d[] = { seq }; \ > - struct device *dev = &dsi->dev; \ > - int ret; \ > - ret = mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d)); \ > - if (ret < 0) { \ > - dev_err_ratelimited(dev, "transmit data failed: %d\n", \ > - ret); \ > - return ret; \ > - } \ > +#define mipi_dsi_generic_write_seq(dsi, seq...) \ > + do { \ > + static const u8 d[] = { seq }; \ > + struct device *dev = &dsi->dev; \ > + ssize_t ret; \ > + ret = mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d)); \ > + if (ret < 0) { \ > + dev_err_ratelimited(dev, "transmit data failed: %zd\n", \ > + ret); \ > + return ret; \ > + } \ > } while (0) > > /**
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
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