File 1267-Make-binary_to_term-1-more-resilent-agains... of Package erlang

Overview Repositories Revisions Requests Users Attributes Meta

File 1267-Make-binary_to_term-1-more-resilent-against-bad-bina.patch of Package erlang

From 81805d631b6e196f2a71abc58b0c469186bec58e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Wed, 1 Sep 2021 08:13:05 +0200
Subject: [PATCH] Make binary_to_term/1 more resilent against bad binaries

binary_to_term/1 could crash the runtime system when given a
corrupted binary containing the external representation of
maps.

This commit fixes two issues:

* There could multiple frees of the same memory area for
a corrupted term containing both large maps and small maps.

* Heap space would be allocated according to the number of elements
the map was supposed to contain, even if the binary was clearly too
short to contain that many elements.
---
 erts/emulator/beam/external.c       |  5 ++++-
 erts/emulator/test/binary_SUITE.erl | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/erts/emulator/beam/external.c b/erts/emulator/beam/external.c
index c8d0bf7f40..feb7cd7a49 100644
--- a/erts/emulator/beam/external.c
+++ b/erts/emulator/beam/external.c
@@ -4248,7 +4248,6 @@ dec_term_atom_common:
 
             (void) PSTACK_POP(hamt_array);
         } while (!PSTACK_IS_EMPTY(hamt_array));
-        PSTACK_DESTROY(hamt_array);
     }
 
     /* Iterate through all the (flat)maps and check for validity and sort keys
@@ -4260,6 +4259,9 @@ dec_term_atom_common:
         if (!erts_validate_and_sort_flatmap((flatmap_t*)next))
             goto error;
     }
+
+    /* Now that no more errors can occur, the stacks can be destroyed safely. */
+    PSTACK_DESTROY(hamt_array);
     WSTACK_DESTROY(flat_maps);
 
     ASSERT((Eterm*)*dbg_resultp != NULL);
@@ -4846,6 +4848,7 @@ init_done:
             if (n <= MAP_SMALL_MAP_LIMIT) {
                 heap_size += 3 + n + 1 + n;
             } else {
+                CHKSIZE(2*n);   /* Conservative size check */
                 heap_size += HASHMAP_ESTIMATED_HEAP_SIZE(n);
             }
 	    break;
diff --git a/erts/emulator/test/binary_SUITE.erl b/erts/emulator/test/binary_SUITE.erl
index 06db9d3ff3..c4ebe2ab3b 100644
--- a/erts/emulator/test/binary_SUITE.erl
+++ b/erts/emulator/test/binary_SUITE.erl
@@ -1408,6 +1408,22 @@ test_terms(Test_Func) ->
     Test_Func(FF = fun binary_SUITE:all/0),
     Test_Func(lists:duplicate(32, FF)),
 
+    %% Maps.
+    SmallMap = #{a => 1, b => 2, c => 3},
+    LargeMap1 = maps:from_list([{list_to_atom(integer_to_list(36#cafe+N*N*N, 36)),N} ||
+                                   N <- lists:seq(1, 33)]),
+    LargeMap2 = maps:from_list([{list_to_atom(integer_to_list(36#dead+N, 36)),N} ||
+                                   N <- lists:seq(1, 50)]),
+    MapWithMap = LargeMap1#{SmallMap => a, LargeMap1 => LargeMap2, LargeMap2 => LargeMap1,
+                            [LargeMap1,LargeMap2] => LargeMap1,
+                            <<"abc">> => SmallMap, <<"qrs">> => LargeMap1,
+                            <<"xyz">> => LargeMap2 },
+    Test_Func(#{}),
+    Test_Func(SmallMap),
+    Test_Func(LargeMap1),
+    Test_Func(LargeMap2),
+    Test_Func(MapWithMap),
+
     ok.
 
 test_floats(Test_Func) ->
-- 
2.31.1

Places

File 1267-Make-binary_to_term-1-more-resilent-against-bad-bina.patch of Package erlang

Places