| Message ID | 20230905185329.26934-1-hamza.mahfooz@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/amd/display: prevent potential division by zero errors | expand |
On 2023-09-05 14:53, Hamza Mahfooz wrote: > There are two places in apply_below_the_range() where it's possible for > a divide by zero error to occur. So, to fix this make sure the divisor > is non-zero before attempting the computation in both cases. > > Cc: stable@vger.kernel.org > Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2637 > Fixes: a463b263032f ("drm/amd/display: Fix frames_to_insert math") > Fixes: ded6119e825a ("drm/amd/display: Reinstate LFC optimization") > Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com> > --- > drivers/gpu/drm/amd/display/modules/freesync/freesync.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c > index dbd60811f95d..ef3a67409021 100644 > --- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c > +++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c > @@ -338,7 +338,9 @@ static void apply_below_the_range(struct core_freesync *core_freesync, > * - Delta for CEIL: delta_from_mid_point_in_us_1 > * - Delta for FLOOR: delta_from_mid_point_in_us_2 > */ > - if ((last_render_time_in_us / mid_point_frames_ceil) < in_out_vrr->min_duration_in_us) { > + if (mid_point_frames_ceil && > + (last_render_time_in_us / mid_point_frames_ceil) < > + in_out_vrr->min_duration_in_us) { > /* Check for out of range. > * If using CEIL produces a value that is out of range, > * then we are forced to use FLOOR. > @@ -385,8 +387,9 @@ static void apply_below_the_range(struct core_freesync *core_freesync, > /* Either we've calculated the number of frames to insert, > * or we need to insert min duration frames > */ > - if (last_render_time_in_us / frames_to_insert < > - in_out_vrr->min_duration_in_us){ > + if (frames_to_insert && > + (last_render_time_in_us / frames_to_insert) < > + in_out_vrr->min_duration_in_us){ > frames_to_insert -= (frames_to_insert > 1) ? > 1 : 0; > } Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com> -- Thanks & Regards, Jay
diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c index dbd60811f95d..ef3a67409021 100644 --- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c +++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c @@ -338,7 +338,9 @@ static void apply_below_the_range(struct core_freesync *core_freesync, * - Delta for CEIL: delta_from_mid_point_in_us_1 * - Delta for FLOOR: delta_from_mid_point_in_us_2 */ - if ((last_render_time_in_us / mid_point_frames_ceil) < in_out_vrr->min_duration_in_us) { + if (mid_point_frames_ceil && + (last_render_time_in_us / mid_point_frames_ceil) < + in_out_vrr->min_duration_in_us) { /* Check for out of range. * If using CEIL produces a value that is out of range, * then we are forced to use FLOOR. @@ -385,8 +387,9 @@ static void apply_below_the_range(struct core_freesync *core_freesync, /* Either we've calculated the number of frames to insert, * or we need to insert min duration frames */ - if (last_render_time_in_us / frames_to_insert < - in_out_vrr->min_duration_in_us){ + if (frames_to_insert && + (last_render_time_in_us / frames_to_insert) < + in_out_vrr->min_duration_in_us){ frames_to_insert -= (frames_to_insert > 1) ? 1 : 0; }
There are two places in apply_below_the_range() where it's possible for a divide by zero error to occur. So, to fix this make sure the divisor is non-zero before attempting the computation in both cases. Cc: stable@vger.kernel.org Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2637 Fixes: a463b263032f ("drm/amd/display: Fix frames_to_insert math") Fixes: ded6119e825a ("drm/amd/display: Reinstate LFC optimization") Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com> --- drivers/gpu/drm/amd/display/modules/freesync/freesync.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)