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| author | Björn Gustavsson <[email protected]> | 2018-01-04 13:28:22 +0100 |
|---|---|---|
| committer | Björn Gustavsson <[email protected]> | 2018-01-08 08:06:43 +0100 |
| commit | 1ee21858db7e55b15c2f947ddfa00ae5af5c009d (patch) | |
| tree | 4d2607eeeae3015bc2eb3499aca305083ac6f078 | |
| parent | 31782c3accacafb20bc7efd46004921aea8f9f22 (diff) | |
| download | otp-1ee21858db7e55b15c2f947ddfa00ae5af5c009d.tar.gz otp-1ee21858db7e55b15c2f947ddfa00ae5af5c009d.tar.bz2 otp-1ee21858db7e55b15c2f947ddfa00ae5af5c009d.zip | |
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.erl | 2 | ||||
| -rw-r--r-- | lib/compiler/src/beam_validator.erl | 7 |
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). |