[pve-devel] [PATCH qemu-server] anchor CPU flag regex to avoid arbitrary flag suffixes

[Stefan Reiter <s.reiter@proxmox.com>]

Previously one could specify a CPU flag like 'pcidfoobar' and it would
be accepted, even though we attempt to filter VM-only flags for
security. AFAICT none of the flags we allow can be turned into any
others just by appending text, but better safe than sorry.

Reported-by: Oguz Bektas <o.bektas@proxmox.com>
Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
---
 PVE/QemuServer/CPUConfig.pm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/PVE/QemuServer/CPUConfig.pm b/PVE/QemuServer/CPUConfig.pm
index 32192f2..b9981c8 100644
--- a/PVE/QemuServer/CPUConfig.pm
+++ b/PVE/QemuServer/CPUConfig.pm
@@ -214,7 +214,7 @@ sub validate_vm_cpu_conf {
     # in a VM-specific config, certain properties are limited/forbidden
 
     die "VM-specific CPU flags must be a subset of: @{[join(', ', @supported_cpu_flags)]}\n"
-	if ($cpu->{flags} && $cpu->{flags} !~ m/$cpu_flag_supported_re(;$cpu_flag_supported_re)*/);
+	if ($cpu->{flags} && $cpu->{flags} !~ m/^$cpu_flag_supported_re(;$cpu_flag_supported_re)*$/);
 
     die "Property 'reported-model' not allowed in VM-specific CPU config.\n"
 	if defined($cpu->{'reported-model'});
@@ -442,7 +442,7 @@ sub parse_cpuflag_list {
     return $res if !$flaglist;
 
     foreach my $flag (split(";", $flaglist)) {
-	if ($flag =~ $re) {
+	if ($flag =~ m/^$re$/) {
 	    $res->{$2} = { op => $1, reason => $reason };
 	}
     }
-- 
2.20.1