Bug 190061

Summary: "Fix invalid FPU ptrace" causes 32-bit bash to crash
Product: Platform Specific/Hardware Reporter: Jan Steffens (jan.steffens)
Component: x86-64Assignee: platform_x86_64 (platform_x86_64)
Status: NEW ---    
Severity: normal CC: pnyberg
Priority: P1    
Hardware: x86-64   
OS: Linux   
Kernel Version: 4.9.9 Subsystem:
Regression: Yes Bisected commit-id:

Description Jan Steffens 2016-12-11 16:14:11 UTC 
Recently our build server started to have problems building packages (e.g. gtk3 and linux) in i686 chroots. Bash would seemingly randomly complain about unexpected EOF and also crash in malloc.

A simple test is "valgrind bash" which immediately crashes.

Eventually I reduced it to the kernel and bisected it to commit 885bad1e5 (x86/fpu: Fix invalid FPU ptrace state after execve()) which was introduced to the stable tree in 4.8.12.

Reverting this commit makes things work again.

Both the build server and my laptop (where I could reproduce the issue) use Skylake CPUs. Frustratingly, I could not reproduce the issue in a VM running on the build server.

kernel 4.8.13-1-ARCH (Arch Linux)
Comment 1 pnyberg 2017-01-23 08:25:22 UTC 
I am also having issues with this, having my 32-bit hello world program crashing valgrind. Please see my ticket on the valgrind bugzilla: https://bugs.kde.org/show_bug.cgi?id=375171
Comment 2 Jan Steffens 2017-01-23 11:55:05 UTC 
Our build server is also running a Skylake processor (Xeon E3-1275 v5).
Comment 3 pnyberg 2017-01-23 14:11:52 UTC 
We are seeing the problem on both i5-6500u and i7-6600u, haven't tested on any other Skylake CPUs.
Comment 4 pnyberg 2017-01-23 14:14:52 UTC 
(In reply to pnyberg from comment #3)
> We are seeing the problem on both i5-6500u and i7-6600u, haven't tested on
> any other Skylake CPUs.

Sorry, we are seeing it on i5-6200U and i7-6600U.
Comment 5 Jan Steffens 2017-02-09 18:28:53 UTC 
Still relevant as of 4.9.9.
Comment 6 Jan Steffens 2017-02-18 18:29:00 UTC 
Seems this got fixed in 4.9.11 (commit 724aedaa5ca6dfa31e54864f03215cce7ed663a0). Thanks.