Re: [BUG][4.5.1]xl cpupool-create segfault (with config file parameter)

[Benjamin Beier <benjamin@desaster-games.com>]

On 08/12/2015 01:28 PM, Ian Campbell wrote:
> On Wed, 2015-08-12 at 13:03 +0200, Benjamin Beier wrote:
>> Since xen version 4.5.1 there is a bug with the xl cpupool-create
>> command.
>> It always throws a segmentation fault when used with a config file as
>> parameter.
>> The content of the config file does not really matter (valid or invalid).
>> It also fails with the example config file in /etc/xen/cpupool or with
>> the dryrun flag.
>> You never get any output apart from "segmentation fault".
>> If you create exactly the same cpupool without using a config file it
>> works absolutely fine.
>> Tested on multiple systems and it seems to be reproducible for everyone.
>> STrace shows that the command fails right after reading the content of
>> the config file.
>
> Please can you capture a backtrace by running it under gdb. Valgrind might
> also have something interesting to say.
>
> FWIW this doesn't happen on the current development branch:
>      # cat foo
>      Testing
>      # xl cpupool-create foo
>      foo:1: config parsing error near `Testing': lexical error
>      Failed to parse config file: Invalid argument
>
> But I don't see any obviously related looking fixes in the commit log.
>
> Was 4.5.0 ok?

I am not 100% sure about that, because I only had a test system running 
with it.
As you guys didn't notice any problems I should mention that my servers 
are running Gentoo Linux.
Maybe this is a Gentoo specific problem and not relevant at all for 
upstream xen.
Or it is an upstream problem that only shows up on the custom-compiled 
gentoo systems.

# cat testing
foo

# xl cpupool-create testing
Segmentation fault

# strace xl cpupool-create testing
(...)
open("testing", O_RDONLY)               = 7
fstat(7, {st_mode=S_IFREG|0644, st_size=4, ...}) = 0
fstat(7, {st_mode=S_IFREG|0644, st_size=4, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) 
= 0x776ec3228000
read(7, "foo\n", 4096)                  = 4
close(7)                                = 0
munmap(0x776ec3228000, 4096)            = 0
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0} ---
+++ killed by SIGSEGV (core dumped) +++
Segmentation fault

Program received signal SIGSEGV, Segmentation fault.
0x0000000000418db5 in main_cpupoolcreate (argc=<optimized out>, 
argv=0x7fffffffda50) at xl_cmdimpl.c:7102
7102    xl_cmdimpl.c: No such file or directory.
(gdb) bt
#0  0x0000000000418db5 in main_cpupoolcreate (argc=<optimized out>, 
argv=0x7fffffffda50) at xl_cmdimpl.c:7102
#1  0x0000000000407c79 in main (argc=2, argv=0x7fffffffda50) at xl.c:361

Just tell me if this is a gentoo-only thing and I will open a bug report 
there.

Regards,
Benjamin