Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
Pre-existing issues: - [Medium] Unchecked `vrefresh` parameter from kernel command line can cause multiple divide-by-zero panics. -- --- Patch [1]: [PATCH] drm/modes: reject out-of-range GTF blanking duty cycle --- commit c78fc29b3d453bf33d5cd88746572b5f1e9a5c60 Author: Xiang Mei <[email protected]> drm/modes: reject out-of-range GTF blanking duty cycle This commit rejects GTF blanking duty cycles of 100% or more to prevent a divide-by-zero error that occurs when the divisor (100000 - ideal_duty_cycle) evaluates to 0. > diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c > index e1eed13a8e94f..291037706b587 100644 > --- a/drivers/gpu/drm/drm_modes.c > +++ b/drivers/gpu/drm/drm_modes.c > @@ -966,6 +966,10 @@ drm_gtf_mode_complex(struct drm_device *dev, int > hdisplay, int vdisplay, > /* 18.Find the ideal blanking duty cycle from blanking duty cycle */ > ideal_duty_cycle = GTF_C_PRIME * 1000 - > (GTF_M_PRIME * 1000000 / hfreq_est); [Severity: Medium] This is a pre-existing issue, but while fixing divide-by-zero crashes here, could an unvalidated vrefresh parameter cause other divide-by-zero panics in this function? For example, if an administrator provides a kernel command line parameter with a refresh rate of @0 (e.g., video=1024x768@0), vfieldrate_rqd evaluates to 0. This would cause a panic earlier in drm_gtf_mode_complex(): hperiod = 1000000 / (vfieldrate_rqd * vtotal_lines); Also, if the refresh rate is @1818, tmp1 evaluates to 0: tmp1 = (1000000 - MIN_VSYNC_PLUS_BP * vfieldrate_rqd) / 500; // (1000000 - 550 * 1818) / 500 = 0 This leads to another direct division by zero: hfreq_est = (tmp2 * 1000 * vfieldrate_rqd) / tmp1; And if hfreq_est evaluates to 0, it causes a third divide-by-zero on the ideal_duty_cycle assignment above. Should drm_gtf_mode_complex() validate the vrefresh parameter before performing these calculations? > + if (ideal_duty_cycle >= 100000) { > + drm_mode_destroy(dev, drm_mode); > + return NULL; > + } > /* 19.Find the number of pixels in the blanking time to the nearest > * double character cell: */ > hblank = total_active_pixels * ideal_duty_cycle / -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=1
