Bug 31617

Summary:	Radeon/Compiz: 'failed to attach dri2 front buffer', error case not handled
Product:	Mesa	Reporter:	Daniel Lichtenberger <daniel.lichtenberger>
Component:	Drivers/DRI/R600	Assignee:	Default DRI bug account <dri-devel>
Status:	RESOLVED FIXED	QA Contact:
Severity:	normal
Priority:	medium
Version:	7.9
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Attachments:	backtrace

Description Daniel Lichtenberger 2010-11-14 04:10:14 UTC

Created attachment 40267 [details]
backtrace

System: Fedora 14, Radeon 4850, x86_64.

Using the system's mesa-dri-drivers package Compiz frequently crashes while resizing windows. The backtrace (attached) and the error message, "failed to attach dri2 front buffer XX", point to radeon_update_renderbuffers in radeon_common_context.c around line 745:

            bo = radeon_bo_open(...);

            if (bo == NULL) {

                fprintf(stderr, "failed to attach %s %d\n",
                    regname, buffers[i].name);

            }

            ret = radeon_bo_get_tiling(bo, &tiling_flags, &pitch);


An error message is printed when 'bo' could not be allocated, but bo is then happily dereferenced in radeon_bo_get_tiling afterwards. Working around the null pointer dereference (e.g. by adding a 'continue' in the "if bo==NULL" block) fixes the crash for me and I haven't seen visual artifacts yet, although the error message is printed from time to time while running Compiz.

The same stacktrace was logged by several people over at https://bugzilla.redhat.com/show_bug.cgi?id=568593.

Comment 1 Alex Deucher 2010-11-14 22:37:36 UTC

Thanks.  Fix pushed to master:
ef0720758e5ba34d0d163bdf5efc6e8dabd65aa8
and 7.9:
9b1ac4d127805f6a14415596e4a557fad3d570a5

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