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-rw-r--r--erts/emulator/beam/beam_emu.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index 78ab6fa30f..592cfe273f 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -4326,7 +4326,19 @@ void process_main(void)
flags = Arg(2);
BsGetFieldSize(tmp_arg2, (flags >> 3), ClauseFail(), size);
if (size >= SMALL_BITS) {
- Uint wordsneeded = 1+WSIZE(NBYTES((Uint) size));
+ Uint wordsneeded;
+ /* check bits size before potential gc.
+ * We do not want a gc and then realize we don't need
+ * the allocated space (i.e. if the op fails)
+ *
+ * remember to reacquire the matchbuffer after gc.
+ */
+
+ mb = ms_matchbuffer(tmp_arg1);
+ if (mb->size - mb->offset < size) {
+ ClauseFail();
+ }
+ wordsneeded = 1+WSIZE(NBYTES((Uint) size));
TestHeapPreserve(wordsneeded, Arg(1), tmp_arg1);
}
mb = ms_matchbuffer(tmp_arg1);