http://bugs.freedesktop.org/show_bug.cgi?id=65210
Commit 37d956e3ac9513b74078882dff489f9b0a7a5a28 presets config->compat_output = -1 to signal an unset compat_output. Since compat_output is used to index config->output[] during initial screen configuration a bad dereference occurs. At this point the compatibility output can't be known so a NULL return from xf86CompatOutput(ScrnInfoPtr pScrn) is a logical solution. -------------------------------- http://lists.x.org/archives/xorg-devel/2013-March/035751.html If there is no compat output, config->compat_output is -1 and xf86CompatOutput reads before the beginning of the outputs array. Invalid read of size 8 at 0x4DB892: xf86CompatOutput (xf86Crtc.h:734) by 0x4E285D: xf86OutputSetEDID (xf86Crtc.c:2986) by 0x862200F: intel_output_attach_edid (intel_display.c:895) by 0x86222A5: intel_output_get_modes (intel_display.c:955) by 0x4DF296: xf86ProbeOutputModes (xf86Crtc.c:1586) by 0x4E1349: xf86InitialConfiguration (xf86Crtc.c:2380) by 0x8623F72: intel_mode_pre_init (intel_display.c:1788) by 0x8626088: I830PreInit (intel_driver.c:625) by 0x49873B: InitOutput (xf86Init.c:606) by 0x4257B8: main (main.c:204) Address 0x7955d88 is 8 bytes before a block of size 16 alloc'd at 0x4C2C25E: realloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) by 0x4DCD54: xf86OutputCreate (xf86Crtc.c:621) by 0x862322F: intel_output_init (intel_display.c:1416) by 0x8623F22: intel_mode_pre_init (intel_display.c:1780) by 0x8626088: I830PreInit (intel_driver.c:625) by 0x49873B: InitOutput (xf86Init.c:606) by 0x4257B8: main (main.c:204) Signed-off-by: Aaron Plattner <[email protected]> --- hw/xfree86/modes/xf86Crtc.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/hw/xfree86/modes/xf86Crtc.h b/hw/xfree86/modes/xf86Crtc.h index 802303f..1ac8485 100644 --- a/hw/xfree86/modes/xf86Crtc.h +++ b/hw/xfree86/modes/xf86Crtc.h @@ -731,6 +731,8 @@ xf86CompatOutput(ScrnInfoPtr pScrn) { xf86CrtcConfigPtr config = XF86_CRTC_CONFIG_PTR(pScrn); + if (config->compat_output < 0) + return NULL; return config->output[config->compat_output]; } -- 1.8.2 _______________________________________________ [email protected]: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel
