From 1e6ab2fdac21c7847b7fda32fed1ea35883a535e Mon Sep 17 00:00:00 2001 From: Tomas Abrahamsson Date: Thu, 13 Dec 2018 22:36:03 +0100 Subject: erts: Fix possible heap corruption getting atomics Due to comparison as a signed integer, when getting an unsigned atomic in the range 2^63-1..2^64-1 (when the most significant bit was set), the heap could get corrupted when the integer was retrieved: hsz would get set to zero, but the code proceeded to build a bignum. Steps to reproduce (at least on x86_64): $ erl 1> A = atomics:new(1,[{signed,false}]). 2> atomics:put(A,1,18446744073709551615). 3> atomics:get(A,1). At the last step, the shell would print some garbage and hang. --- erts/emulator/test/atomics_SUITE.erl | 3 +++ 1 file changed, 3 insertions(+) (limited to 'erts/emulator/test') diff --git a/erts/emulator/test/atomics_SUITE.erl b/erts/emulator/test/atomics_SUITE.erl index 8c42354770..a5407c42ee 100644 --- a/erts/emulator/test/atomics_SUITE.erl +++ b/erts/emulator/test/atomics_SUITE.erl @@ -126,6 +126,9 @@ unsigned_limits(Config) when is_list(Config) -> Min = atomics:add_get(Ref, 1, 1), Max = atomics:sub_get(Ref, 1, 1), + atomics:put(Ref, 1, Max), + io:format("Max=~p~n", [atomics:get(Ref, 1)]), + {'EXIT',{badarg,_}} = (catch atomics:add(Ref, 1, Max+1)), IncrMin = -(1 bsl (Bits-1)), ok = atomics:put(Ref, 1, -IncrMin), -- cgit v1.2.3