From dfe1c58c504531361fa3f8ed874238a9ff552640 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Mon, 29 Jun 2015 13:24:31 +0200 Subject: beam_makeops: Eliminate crash because of unsafe packing Consider an hypothetical instruction: do_something x x c The loader would crash if we tried to load an instance of the instruction with the last operand referencing a literal: {do_something,{x,0},{x,1},{literal,{a,b,c}}} Teach beam_makeops to turn off packing for such unsafe instructions. --- erts/emulator/utils/beam_makeops | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'erts/emulator') diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops index e90ed94187..7c94546ea4 100755 --- a/erts/emulator/utils/beam_makeops +++ b/erts/emulator/utils/beam_makeops @@ -1057,6 +1057,7 @@ sub do_pack { my($packable_args) = 0; my @is_packable; # Packability (boolean) for each argument. my $wide_packing = 0; + my(@orig_args) = @args; # # Count the number of packable arguments. If we encounter any 's' or 'd' @@ -1077,6 +1078,18 @@ sub do_pack { } } elsif ($arg =~ /^[sd]/) { return ('', '', @args); + } elsif ($arg =~ /^[scq]/ and $packable_args > 0) { + # When packing, this operand will be picked up from the + # code array, put onto the packing stack, and later put + # back into a different location in the code. The problem + # is that if this operand is a literal, the original + # location in the code would have been remembered in a + # literal patch. For packing to work, we would have to + # adjust the position in the literal patch. For the + # moment, adding additional instructions to the packing + # engine to handle this does not seem worth it, so we will + # just turn off packing. + return ('', '', @args); } else { push @is_packable, 0; } -- cgit v1.2.3