On Thu, Mar 1, 2018 at 11:06 PM, Tobin C. Harding <m...@tobin.cc> wrote: > On Tue, Feb 27, 2018 at 03:45:09PM +1100, Tobin C. Harding wrote: >> When the system is idle it is likely that most files under /proc/PID >> will be identical for various processes. Scanning _all_ the PIDs under >> /proc is unnecessary and implies that we are thoroughly scanning /proc. >> This is _not_ the case because there may be ways userspace can trigger >> creation of /proc files that leak addresses but were not present during >> a scan. For these two reasons we should exclude all PID directories >> under /proc except '1/' >> >> Exclude all /proc/PID except /proc/1. >> >> Signed-off-by: Tobin C. Harding <m...@tobin.cc> >> --- >> scripts/leaking_addresses.pl | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/scripts/leaking_addresses.pl b/scripts/leaking_addresses.pl >> index 6e5bc57caeaa..fb40e2828f43 100755 >> --- a/scripts/leaking_addresses.pl >> +++ b/scripts/leaking_addresses.pl >> @@ -10,6 +10,14 @@ >> # Use --debug to output path before parsing, this is useful to find files >> that >> # cause the script to choke. >> >> +# >> +# When the system is idle it is likely that most files under /proc/PID will >> be >> +# identical for various processes. Scanning _all_ the PIDs under /proc is >> +# unnecessary and implies that we are thoroughly scanning /proc. This is >> _not_ >> +# the case because there may be ways userspace can trigger creation of /proc >> +# files that leak addresses but were not present during a scan. For these >> two >> +# reasons we exclude all PID directories under /proc except '1/' >> + >> use warnings; >> use strict; >> use POSIX; >> @@ -472,6 +480,9 @@ sub walk >> my $path = "$pwd/$file"; >> next if (-l $path); >> >> + # skip /proc/PID except /proc/1 >> + next if ($path =~ /\/proc\/(?:[2-9][0-9]*|1[0-9]+)/); > > Perhaps the intent of this is clearer? > > next if (($path =~ /^\/proc\/[0-9]+$/) && > ($path !~ /^\/proc\/1$/)); > > > thanks, > Tobin.
Hi Tobin, The intent is crystal clear now. Thanks. Here's something that generates the same output as the code above: next if ($path !~ "^/proc/(1|[^0-9]+)\$"); I'm not insisting this be given any preference whatsoever. Thanks.
