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| author | Tomas Abrahamsson <[email protected]> | 2018-12-13 22:36:03 +0100 |
|---|---|---|
| committer | Tomas Abrahamsson <[email protected]> | 2018-12-13 22:36:03 +0100 |
| commit | 1e6ab2fdac21c7847b7fda32fed1ea35883a535e (patch) | |
| tree | f6ca6afe4af45f3f8f95070924bceaf79d820e69 /erts/emulator | |
| parent | 3825199794da28d79b21052a2e69e2335921d55e (diff) | |
| download | otp-1e6ab2fdac21c7847b7fda32fed1ea35883a535e.tar.gz otp-1e6ab2fdac21c7847b7fda32fed1ea35883a535e.tar.bz2 otp-1e6ab2fdac21c7847b7fda32fed1ea35883a535e.zip | |
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.
Diffstat (limited to 'erts/emulator')
| -rw-r--r-- | erts/emulator/beam/erl_bif_atomics.c | 2 | ||||
| -rw-r--r-- | erts/emulator/test/atomics_SUITE.erl | 3 |
2 files changed, 4 insertions, 1 deletions
diff --git a/erts/emulator/beam/erl_bif_atomics.c b/erts/emulator/beam/erl_bif_atomics.c index 092dbb3bd3..029831bd95 100644 --- a/erts/emulator/beam/erl_bif_atomics.c +++ b/erts/emulator/beam/erl_bif_atomics.c @@ -133,7 +133,7 @@ static ERTS_INLINE Eterm bld_atomic(Process* proc, AtomicsRef* p, if ((Uint64)val <= MAX_SMALL) return make_small((Sint) val); else { - Uint hsz = ERTS_UINT64_HEAP_SIZE(val); + Uint hsz = ERTS_UINT64_HEAP_SIZE((Uint64)val); Eterm* hp = HAlloc(proc, hsz); return erts_uint64_to_big(val, &hp); } 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), |