From: Chris Wilson Date: Fri, 27 Nov 2009 13:06:56 +0000 (+0000) Subject: drm/i915: Avoid NULL dereference with component_only tv_modes X-Git-Tag: v2.6.33-rc2~19^2~29^2~30 X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=commitdiff_plain;h=d271817baecbccb47da0d9f28c285a0dae8a06b7 drm/i915: Avoid NULL dereference with component_only tv_modes In commit d2d9f2324, the guard for a valid video mode was removed. This caused the regression: kernel crash during kms graphic boot on Intel GM4500 platform https://bugzilla.redhat.com/show_bug.cgi?id=540218 This patches changes the logic slightly not to rely on a coupled variable, but to just check whether the video_modes is valid before dereferencing. Signed-off-by: Chris Wilson Cc: David Woodhouse Cc: Zhenyu Wang [ickle: Actually reference the correct bug report] Acked-by: Zhenyu Wang Signed-off-by: Eric Anholt --- diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c index a0e4bc4..d7465ca 100644 --- a/drivers/gpu/drm/i915/intel_tv.c +++ b/drivers/gpu/drm/i915/intel_tv.c @@ -1213,20 +1213,17 @@ intel_tv_mode_set(struct drm_encoder *encoder, struct drm_display_mode *mode, tv_ctl |= TV_TRILEVEL_SYNC; if (tv_mode->pal_burst) tv_ctl |= TV_PAL_BURST; + scctl1 = 0; - /* dda1 implies valid video levels */ - if (tv_mode->dda1_inc) { + if (tv_mode->dda1_inc) scctl1 |= TV_SC_DDA1_EN; - } - if (tv_mode->dda2_inc) scctl1 |= TV_SC_DDA2_EN; - if (tv_mode->dda3_inc) scctl1 |= TV_SC_DDA3_EN; - scctl1 |= tv_mode->sc_reset; - scctl1 |= video_levels->burst << TV_BURST_LEVEL_SHIFT; + if (video_levels) + scctl1 |= video_levels->burst << TV_BURST_LEVEL_SHIFT; scctl1 |= tv_mode->dda1_inc << TV_SCDDA1_INC_SHIFT; scctl2 = tv_mode->dda2_size << TV_SCDDA2_SIZE_SHIFT |