Hello,
I found an uninitialized memory in mesa dri that leads to a segfault, yet I do
not know how or if to file a bugreport.
I tried to play AlienArena2008 (v7.20) and it segfaulted. By running it in gdb
I noticed the segfault happens in driReportDamage, dri_util.c:438 of Mesa 7.2.
. There is a line "(*psp->damage->reportDamage)(...);" which makes a call to a
function pointer. By looking at the variables, I noticed that "psp->damage" has
nonsense-values.
psp->damage is neither zero nor pointing to valid memory (debuger tells me
*psp->damage: memory not accessable). It looks like uninitialized memory and
obviously leads to the segfault.
AFAICS the relevant structure is created in function driCreateNewScreen() (in
dri_util.c:833). Memory is allocated there and then part of the structure is
initialzed, but psp->damage is obviously not initialized.
I patched that part of the driver so that the whole structure is initialized
with zeros (before any other inits). After building and installing mesa again,
the segfault in Mesa is gone and I could play AlienArena.
So, is this a bug in mesa or am I just using an invalid configuration (e.g. old
xserver) ?
System configuration:
- debian etch
- lspci|grep Display
06:00.1 Display controller: ATI Technologies Inc RV370 [Radeon X300SE]
- dpkg -l xserver-xorg
xserver-xorg 7.1.0-19
- self-compiled drm from current git
- self-compiled mesa 7.2
If it is a bug, is my fix the correct solution ? Or is sth else responsible for
initing the memory or not using the uninited memory ? Or is my solution
acceptable as a workaround at least ?
Bye,
Wolfgang
--- Mesa-7.2/src/mesa/drivers/dri/common/dri_util.c 2008-08-25
16:46:43.000000000 +0200
+++ Mesa-7.2-fixed/src/mesa/drivers/dri/common/dri_util.c 2008-11-09
01:21:03.000000000 +0100
@@ -847,6 +847,7 @@
if (!psp)
return NULL;
+ memset(psp,0,sizeof(*psp));
setupLoaderExtensions(psp, extensions);
/*
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