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authorBjörn Gustavsson <[email protected]>2018-01-04 13:28:22 +0100
committerBjörn Gustavsson <[email protected]>2018-01-08 08:06:43 +0100
commit1ee21858db7e55b15c2f947ddfa00ae5af5c009d (patch)
tree4d2607eeeae3015bc2eb3499aca305083ac6f078
parent31782c3accacafb20bc7efd46004921aea8f9f22 (diff)
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beam_validator: Strengthen validation of GC instructions
beam_validator did not verify that the Y registers were initialized before executing the following instructions that could cause a GC: bs_append/8 bs_init2/6 bs_init_bits/6 gc_bif1/5 gc_bif2/6 gc_bif3/7 test_heap/2 That means that, for example, an incorrect optimization that replaced an 'allocate_zero' instruction with an 'allocate' instruction when it was not safe, would not be rejected by beam_validtor, but would instead cause a crash or other undefined behavior at runtime. Also fix a minor bug in beam_type exposed by the stronger checking. When compiling from .S files, beam_type did not handle the init/1 instruction and could produce unsafe code.
-rw-r--r--lib/compiler/src/beam_type.erl2
-rw-r--r--lib/compiler/src/beam_validator.erl7
2 files changed, 8 insertions, 1 deletions
diff --git a/lib/compiler/src/beam_type.erl b/lib/compiler/src/beam_type.erl
index 3d842a6fd3..3446430aaf 100644
--- a/lib/compiler/src/beam_type.erl
+++ b/lib/compiler/src/beam_type.erl
@@ -367,6 +367,8 @@ flt_need_heap_2({set,_,_,get_list}, H, Fl) ->
{[],H,Fl};
flt_need_heap_2({set,_,_,{try_catch,_,_}}, H, Fl) ->
{[],H,Fl};
+flt_need_heap_2({set,_,_,init}, H, Fl) ->
+ {[],H,Fl};
%% All other instructions should cause the insertion of an allocation
%% instruction if needed.
flt_need_heap_2(_, H, Fl) ->
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index be8908dd6b..6219bc6894 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -529,9 +529,10 @@ valfun_4({bif,Op,{f,Fail},Src,Dst}, Vst0) ->
Type = bif_type(Op, Src, Vst),
set_type_reg(Type, Dst, Vst);
valfun_4({gc_bif,Op,{f,Fail},Live,Src,Dst}, #vst{current=St0}=Vst0) ->
+ verify_live(Live, Vst0),
+ verify_y_init(Vst0),
St = kill_heap_allocation(St0),
Vst1 = Vst0#vst{current=St},
- verify_live(Live, Vst1),
Vst2 = branch_state(Fail, Vst1),
Vst = prune_x_regs(Live, Vst2),
validate_src(Src, Vst),
@@ -685,6 +686,7 @@ valfun_4({bs_utf16_size,{f,Fail},A,Dst}, Vst) ->
set_type_reg({integer,[]}, Dst, branch_state(Fail, Vst));
valfun_4({bs_init2,{f,Fail},Sz,Heap,Live,_,Dst}, Vst0) ->
verify_live(Live, Vst0),
+ verify_y_init(Vst0),
if
is_integer(Sz) ->
ok;
@@ -697,6 +699,7 @@ valfun_4({bs_init2,{f,Fail},Sz,Heap,Live,_,Dst}, Vst0) ->
set_type_reg(binary, Dst, Vst);
valfun_4({bs_init_bits,{f,Fail},Sz,Heap,Live,_,Dst}, Vst0) ->
verify_live(Live, Vst0),
+ verify_y_init(Vst0),
if
is_integer(Sz) ->
ok;
@@ -709,6 +712,7 @@ valfun_4({bs_init_bits,{f,Fail},Sz,Heap,Live,_,Dst}, Vst0) ->
set_type_reg(binary, Dst, Vst);
valfun_4({bs_append,{f,Fail},Bits,Heap,Live,_Unit,Bin,_Flags,Dst}, Vst0) ->
verify_live(Live, Vst0),
+ verify_y_init(Vst0),
assert_term(Bits, Vst0),
assert_term(Bin, Vst0),
Vst1 = heap_alloc(Heap, Vst0),
@@ -944,6 +948,7 @@ deallocate(#vst{current=St}=Vst) ->
test_heap(Heap, Live, Vst0) ->
verify_live(Live, Vst0),
+ verify_y_init(Vst0),
Vst = prune_x_regs(Live, Vst0),
heap_alloc(Heap, Vst).