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-rw-r--r--erts/emulator/beam/erl_bits.c31
-rw-r--r--erts/emulator/test/bs_construct_SUITE.erl24
2 files changed, 47 insertions, 8 deletions
diff --git a/erts/emulator/beam/erl_bits.c b/erts/emulator/beam/erl_bits.c
index 71c64997c1..b4e611f01b 100644
--- a/erts/emulator/beam/erl_bits.c
+++ b/erts/emulator/beam/erl_bits.c
@@ -1321,7 +1321,14 @@ erts_bs_append(Process* c_p, Eterm* reg, Uint live, Eterm build_size_term,
goto badarg;
}
}
+
+ if((ERTS_UINT_MAX - build_size_in_bits) < erts_bin_offset) {
+ c_p->freason = SYSTEM_LIMIT;
+ return THE_NON_VALUE;
+ }
+
used_size_in_bits = erts_bin_offset + build_size_in_bits;
+
sb->is_writable = 0; /* Make sure that no one else can write. */
pb->size = NBYTES(used_size_in_bits);
pb->flags |= PB_ACTIVE_WRITER;
@@ -1395,9 +1402,21 @@ erts_bs_append(Process* c_p, Eterm* reg, Uint live, Eterm build_size_term,
goto badarg;
}
}
- used_size_in_bits = erts_bin_offset + build_size_in_bits;
- used_size_in_bytes = NBYTES(used_size_in_bits);
- bin_size = 2*used_size_in_bytes;
+
+ if((ERTS_UINT_MAX - build_size_in_bits) < erts_bin_offset) {
+ c_p->freason = SYSTEM_LIMIT;
+ return THE_NON_VALUE;
+ }
+
+ used_size_in_bits = erts_bin_offset + build_size_in_bits;
+ used_size_in_bytes = NBYTES(used_size_in_bits);
+
+ if(used_size_in_bits < (ERTS_UINT_MAX / 2)) {
+ bin_size = 2 * used_size_in_bytes;
+ } else {
+ bin_size = NBYTES(ERTS_UINT_MAX);
+ }
+
bin_size = (bin_size < 256) ? 256 : bin_size;
/*
@@ -1487,6 +1506,12 @@ erts_bs_private_append(Process* p, Eterm bin, Eterm build_size_term, Uint unit)
* Calculate new size in bytes.
*/
erts_bin_offset = 8*sb->size + sb->bitsize;
+
+ if((ERTS_UINT_MAX - build_size_in_bits) < erts_bin_offset) {
+ p->freason = SYSTEM_LIMIT;
+ return THE_NON_VALUE;
+ }
+
pos_in_bits_after_build = erts_bin_offset + build_size_in_bits;
pb->size = (pos_in_bits_after_build+7) >> 3;
pb->flags |= PB_ACTIVE_WRITER;
diff --git a/erts/emulator/test/bs_construct_SUITE.erl b/erts/emulator/test/bs_construct_SUITE.erl
index b79f4b995d..ce50bcdd86 100644
--- a/erts/emulator/test/bs_construct_SUITE.erl
+++ b/erts/emulator/test/bs_construct_SUITE.erl
@@ -905,14 +905,28 @@ bs_add_overflow(_Config) ->
_ when Memsize < (2 bsl 30) ->
{skip, "Less then 2 GB of memory"};
4 ->
- Large = <<0:((1 bsl 30)-1)>>,
- {'EXIT',{system_limit,_}} =
- (catch <<Large/bits, Large/bits, Large/bits, Large/bits,
- Large/bits, Large/bits, Large/bits, Large/bits,
- Large/bits>>),
+ {'EXIT', {system_limit, _}} = (catch bs_add_overflow_signed()),
+ {'EXIT', {system_limit, _}} = (catch bs_add_overflow_unsigned()),
ok
end.
+bs_add_overflow_signed() ->
+ %% Produce a large result of bs_add that, if cast to signed int, would
+ %% overflow into a negative number that fits a smallnum.
+ Large = <<0:((1 bsl 30)-1)>>,
+ <<Large/bits, Large/bits, Large/bits, Large/bits,
+ Large/bits, Large/bits, Large/bits, Large/bits,
+ Large/bits>>.
+
+bs_add_overflow_unsigned() ->
+ %% Produce a large result of bs_add that goes beyond the limit of an
+ %% unsigned word. This used to succeed but produced an incorrect result
+ %% where B =:= C!
+ A = <<0:((1 bsl 32)-8)>>,
+ B = <<2, 3>>,
+ C = <<A/binary,1,B/binary>>,
+ true = byte_size(B) < byte_size(C).
+
id(I) -> I.
memsize() ->