Re: [pve-devel] [PATCH pve-manager 1/2] fix #5198: ceph: mon: fix mon existence check in mon removal assertion

["Max Carrara" <m.carrara@proxmox.com>]

On Thu Mar 14, 2024 at 8:56 AM CET, Fiona Ebner wrote:
> Am 13.03.24 um 16:42 schrieb Stefan Sterz:
> > On Wed Mar 13, 2024 at 3:53 PM CET, Max Carrara wrote:
> >> The Ceph monitor removal assertion contains a condition that checks
> >> whether the given mon ID actually exists and thus may be removed.
> >>
> >> The first part of the condition checks whether the hash returned by
> >> `get_services_info` [0] contains the key "mon.$monid". However, the
> >> hash's keys are never prefixed with "mon.", which makes this check
> >> incorrect.
> >>
> >> This is fixed by just using "$monid" directly.
> >>
> >> The second part checks whether the mon hashes returned by
> >> Ceph contain the "name" key before comparing the key with the given
> >> mon ID. This key existence check is also incorrect; in particular:
> >>   * If the lookup `$_->{name}` evaluates to e.g. "foo", the check
> >>     passes, because "foo" is truthy. [1]
> >>   * If the lookup `$_->{name}` evaluates to "0", the check fails,
> >>     because "0" is falsy (due to it being equivalent to the number 0,
> >>     according to Perl [1]).
> >>
> >> This is solved by using the inbuilt `exists()` instead of relying on
> >> Perl's definition of truthiness.
> >>
>
> Technically, it's two changes, so could be two patches, but can be fine
> like this too, since both touch the same check.
>
> >> [0]: https://git.proxmox.com/?p=pve-manager.git;a=blob;f=PVE/Ceph/Services.pm;h=e0f31e8eb6bc9b3777b3d0d548497276efaa5c41;hb=HEAD#l112
> >> [1]: https://perldoc.perl.org/perldata#Scalar-values
> >>
> >> Fixes: https://bugzilla.proxmox.com/show_bug.cgi?id=5198
> >> Signed-off-by: Max Carrara <m.carrara@proxmox.com>
> >> ---
> >>  PVE/API2/Ceph/MON.pm | 4 ++--
> >>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/PVE/API2/Ceph/MON.pm b/PVE/API2/Ceph/MON.pm
> >> index 1e959ef3..1737c294 100644
> >> --- a/PVE/API2/Ceph/MON.pm
> >> +++ b/PVE/API2/Ceph/MON.pm
> >> @@ -147,8 +147,8 @@ my $assert_mon_prerequisites = sub {
> >>  my $assert_mon_can_remove = sub {
> >>      my ($monhash, $monlist, $monid, $mondir) = @_;
> >>
> >> -    if (!(defined($monhash->{"mon.$monid"}) ||
> >> -	  grep { $_->{name} && $_->{name} eq $monid } @$monlist))
> > 
> > not sure if splitting the fix and the code style clean up makes sense
> > here but otherwise this works as advertised. So:
> > 
>
> If you already touch the same line, you can also adapt style in one go.
> But since the style change is also done in a second place, which is not
> touched by this patch, it's fine like Max did it too.
>
> > Tested-by: Stefan Sterz <s.sterz@proxmox.com>
> > 
> >> +    if (!(defined($monhash->{$monid}) ||
> >> +	  grep { exists($_->{name}) && $_->{name} eq $monid } @$monlist))
>
> While I suppose we do not expect an entry with undef value here, you do
> not want to compare against undef (just leads to an ugly Perl warning),
> so this should be a definedness check, not an existence check.

Good catch, thanks! Will send in a v2.

>
> >>      {
> >>  	die "no such monitor id '$monid'\n"
> >>      }
> > 
> > 
> > 
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> >