[Impact]
* lshw crashes with SEGV in privileged containers, unless you disable the 'usb' test: $ lshw -disable usb
[Test Case]
## Create a privileged container. ##
$ lxc launch ubuntu:16.04 priv -c security.privileged=true
Creating priv
Starting priv
## Execute lshw inside the privileged container. ##
$ lxc exec priv bash
root@priv:~#
root@priv:~#lshw
Segmentation fault
[Regression Potential]
* Risks of regression are low.
* I have tested lshw inside containers (unprivileges/privileges) and baremetal with success connecting different types of usb device : webcam, usb keys, ... The usb output of lshw cmd is shown as expected, but this time without segfaulting when container in privilege mode.
* Basically, the code look if both files doesn't exists
#define PROCBUSUSBDEVICES "/proc/bus/usb/devices"
#define SYSKERNELDEBUGUSBDEVICES "/sys/kernel/debug/usb/devices"
...
if (!exists(SYSKERNELDEBUGUSBDEVICES) && !exists(PROCBUSUSBDEVICES))
__return false;
I kept the above in place.
But what if only 1 of the 2 files exists ?
For that reason I added an extra verification if SYSKERNELDEBUGUSBDEVICES exist -> fopen SYSKERNELDEBUGUSBDEVICES.
and
if fopen SYSKERNELDEBUGUSBDEVICES fails and PROCBUSUSBDEVICES exist then -> fopen "PROCBUSUSBDEVICES"
The code first look for SYSKERNELDEBUGUSBDEVICES and if it fails it jump to PROCBUSUSBDEVICES.
But if PROCBUSUSBDEVICES fails there was no mechanism to skip, thus segfault.
I also added another if statement in case PROCBUSUSBDEVICES fails like in this situation (no such file or directory) in privileged container, same as if SYSKERNELDEBUGUSBDEVICES can't be opened to force to jump on trying PROCBUSUSBDEVICES.
[Other Info]
* PR :
https://ezix.org/src/pkg/lshw/pulls/9
* Upstream Commit:
https://ezix.org/src/pkg/lshw/commit/7b99d35064230f908551ba65c29264d90f49f246
* This bug doesn't affect Trusty in privileged container. (The code is a bit different in Trusty/lshw package. It basically doesn't rely on SYSKERNELDEBUGUSBDEVICES, meaning that it is only validating if PROCBUSUSBDEVICES exist or not and react accordingly).
* Only affect Xenial and late.
* The bug has been introduced upstream after this specific commit :
https://ezix.org/src/pkg/lshw/commit/9f05be36f7ce6117731e312053d1ec91348a3051
* This particular bug isn't reproducible in Debian (tested with sid in privileged mode) container image because both files doesn't exist in their image, thus making the lshw stop here :
if (!exists(SYSKERNELDEBUGUSBDEVICES) && !exists(PROCBUSUSBDEVICES))
return false;
With that being said, I filed a debian bug anyway mentioning that it would be great for them to merge the upstream PR since Ubuntu is merging/syncing from them, and it won't hurt debian lshw package, if they change or not their image behavior one day. Even if not necessary fixing an actual debian/lshw bug.
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=878792
** Discussion with apw on #ubuntu-release **
[10:45:45] <apw> slashd, artful is open for SRUs, when BB opens it will start from whatever is in A
[11:13:49] <apw> -propsoed gets copied to bb-proposed too yes
[Original Description]
When running lshw in a Xenial container, I'm getting a segmentation fault. I'll attach the apport crash dump.
```
stgraber@castiana:~$ lxc launch ubuntu:16.04 priv -c security.privileged=true
Creating priv
Starting priv
stgraber@castiana:~$ lxc exec priv bash
root@priv:~# lshw
Segmentation fault
root@priv:~#
```
[strace of lshw]
open("/usr/share/hwdata/usb.ids", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/etc/usb.ids", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/usb.ids", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/local/share/usb.ids", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/lshw-common/usb.ids", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/usb.ids", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/sys/kernel/debug/usb/devices", O_RDONLY) = -1 EACCES (Permission denied)
open("/proc/bus/usb/devices", O_RDONLY) = -1 ENOENT (No such file or directory)
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0} ---
+++ killed by SIGSEGV +++
Segmentation fault
However, lshw -disable USB does work fine.