[Nouveau] [Bug 73473] Potential crash bug in src/gallium/auxiliary/rtasm/rtasm_execmem.c

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=73473

--- Comment #2 from Jaak Ristioja <jaak at ristioja.ee> ---
(In reply to comment #1)
> If you're getting consistent crashes in glxgears I would recommend using gdb
> to get a backtrace of the problem.

I wish I could but gdb only shows ?? in backtrace:

(gdb) thread apply all bt full

Thread 1 (process 2782):
#0  0x00006a0a172d4901 in ?? ()
No symbol table info available.
#1  0x0000000000000000 in ?? ()
No symbol table info available.

> With that said, I suspect that the problems is elsewhere for a few reasons
> * There are more than a handful cases when mmap fails and I have yet to
> notice after 3+ years constant use of nouveau any glxgears segfaults.
> * I would suspect other mesa users will be affected and this problem would
> be well know/resolved by now.
> 
> Apart from the backtrace would you mind attaching your dmesg output after
> the problem/segfault ?

[17407.732321] grsec: From 5.4.2.83: denied RWX mmap of <anonymous mapping> by
/usr/bin/glxgears[glxgears:2866] uid/euid:1000/1000 gid/egid:100/100, parent
/bin/bash[bash:2860] uid/euid:1000/1000 gid/egid:100/100
[17407.732328] glxgears[2866]: segfault at ffffffffffffffff ip 0000685b13c99901
sp 000077a968f66e50 error 7 in nouveau_dri.so[685b1381f000+136c000]
[17407.732342] grsec: From 5.4.2.83: Segmentation fault occurred at
ffffffffffffffff in /usr/bin/glxgears[glxgears:2866] uid/euid:1000/1000
gid/egid:100/100, parent /bin/bash[bash:2860] uid/euid:1000/1000
gid/egid:100/100
[17407.732356] grsec: From 5.4.2.83: denied resource overstep by requesting
4096 for RLIMIT_CORE against limit 0 for /usr/bin/glxgears[glxgears:2866]
uid/euid:1000/1000 gid/egid:100/100, parent /bin/bash[bash:2860]
uid/euid:1000/1000 gid/egid:100/100

So it appears to try to read memory at ffffffffffffffff (i.e. -1 alias
MAP_FAILED). It doesn't matter why mmap fails (EPERM). What matters is that it
is documented that it may fail, but errors do not appear to be handled in code.

I don't think Gentoo should be expected to mark every single application using
OpenGL to be allowed mmap RWX memory. I use Intel + OpenGL on my Gentoo
Hardened laptop with no problems.

> Can you reproduce with the swrast driver ?
> $ LIBGL_ALWAYS_SOFTWARE=1 glxgears

$ DISPLAY=:0.0 LIBGL_ALWAYS_SOFTWARE=1 glxgears; echo $?
LLVM ERROR: Allocation failed when allocating new memory in the JIT
Can't allocate RWX Memory: Operation not permitted
1

I'm using Hardened Gentoo (kernel is vanilla-3.12.6 + genpatches-3.12-7 +
grsecurity-3.0-3.12.6-201401021726; gcc --version is "gcc (Gentoo Hardened
4.7.3-r1 p1.4, pie-0.5.5) 4.7.3").

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