On Thu, Jun 15, 2023 at 09:18:38PM +0900, Vincent Mailhol wrote:
Hello,
I am using libguestfs in a Bazel's linux-sandbox environment[1].
When executing in that sandbox environment, I got frequent crashes.
Please find attached below the results of libguestfs-test-tool when
run into that linux-sandbox environment. The most relevant part seems
to be:
[ 0.797233] ldmtool[164]: segfault at 0 ip 0000564a892506a5 sp 00007fff8ee5b900
error 4 in ldmtool[564a8924e000+3000]
[ 0.798117] Code: 18 64 48 33 1c 25 28 00 00 00 75 5e 48 83 c4 28 5b 5d 41 5c 41 5d
41 5e 41 5f c3 66 2e 0f 1f 84 00 00 00 00 00 e8 db fd ff ff <4c> 8b 20 48 89 44 24
08 4c 89 e7 e8 0b e1 ff ff 45 31 c0 4c 89 e1
/init: line 154: 164 Segmentation fault ldmtool create all
So the root cause seems to be around libldm. This mailing list seems
to cover both libguestfs and libldm, so hopefully, I am at the right
place to ask :)
Needless to say, when run outside of the sandbox environment, no crash
were observed.
[1] linux-sandbox.cc
Link:
https://github.com/bazelbuild/bazel/blob/master/src/main/tools/linux-sand...
---
...
supermin: picked /sys/block/sdb/dev (8:16) as root device
supermin: creating /dev/root as block special 8:16
supermin: mounting new root on /root
[ 0.678248] EXT4-fs (sdb): mounting ext2 file system using the ext4 subsystem
[ 0.679832] EXT4-fs (sdb): mounted filesystem without journal. Opts: . Quota mode:
none.
supermin: deleting initramfs files
supermin: chroot
Starting /init script ...
mount: only root can use "--types" option (effective UID is 65534)
/init: line 38: /proc/cmdline: No such file or directory
mount: only root can use "--types" option (effective UID is 65534)
mount: only root can use "--options" option (effective UID is 65534)
mount: only root can use "--types" option (effective UID is 65534)
mount: only root can use "--types" option (effective UID is 65534)
mount: only root can use "--options" option (effective UID is 65534)
It really goes wrong from here, where apparently it's not running as
root (instead UID 65534), even though we're supposed to be running
inside a Linux appliance virtual machine.
Any idea why that would be?
I looked at the sandbox and that would run the qemu process as UID
"nobody" (which might be 65534). However I don't understand why that
would affect anything running on the new kernel inside the appliance.
Rich.
--
Richard Jones, Virtualization Group, Red Hat
http://people.redhat.com/~rjones
Read my programming and virtualization blog:
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