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author | Carl Dong <contact@carldong.me> | 2022-07-01 19:53:04 -0400 |
---|---|---|
committer | Carl Dong <contact@carldong.me> | 2022-08-03 12:02:32 -0400 |
commit | 82d3058539f54ebad745e2b02b61df01aa832a54 (patch) | |
tree | bf8f1d3a99dcb4759179c4926449f39be7b6360a /src/script/sigcache.cpp | |
parent | b370164b319df1a500b70694b077f92265a777fb (diff) | |
download | bitcoin-82d3058539f54ebad745e2b02b61df01aa832a54.tar.xz |
cuckoocache: Check for uint32 overflow in setup_bytes
This fixes an potential overflow which existed prior to this patchset.
If CuckooCache::cache<Element, Hash>::setup_bytes is called with a
`size_t bytes` which, when divided by sizeof(Element), does not fit into
an uint32_t, the implicit conversion to uint32_t in the call to setup
will result in an overflow.
At least on x86_64, this overflow is possible:
static_assert(std::numeric_limits<size_t>::max() / 32 <= std::numeric_limits<uint32_t>::max());
static_assert(std::numeric_limits<size_t>::max() / 4 <= std::numeric_limits<uint32_t>::max());
This commit detects such cases and signals to callers that the `size_t
bytes` input is too large.
Diffstat (limited to 'src/script/sigcache.cpp')
-rw-r--r-- | src/script/sigcache.cpp | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp index 43b594f3cb..507754ad7d 100644 --- a/src/script/sigcache.cpp +++ b/src/script/sigcache.cpp @@ -14,6 +14,7 @@ #include <algorithm> #include <mutex> +#include <optional> #include <shared_mutex> #include <vector> @@ -75,7 +76,7 @@ public: std::unique_lock<std::shared_mutex> lock(cs_sigcache); setValid.insert(entry); } - std::pair<uint32_t, size_t> setup_bytes(size_t n) + std::optional<std::pair<uint32_t, size_t>> setup_bytes(size_t n) { return setValid.setup_bytes(n); } @@ -99,8 +100,9 @@ bool InitSignatureCache() size_t nMaxCacheSize = std::max((int64_t)0, gArgs.GetIntArg("-maxsigcachesize", DEFAULT_MAX_SIG_CACHE_SIZE) / 2) * ((size_t) 1 << 20); auto setup_results = signatureCache.setup_bytes(nMaxCacheSize); + if (!setup_results) return false; - const auto [num_elems, approx_size_bytes] = setup_results; + const auto [num_elems, approx_size_bytes] = *setup_results; LogPrintf("Using %zu MiB out of %zu/2 requested for signature cache, able to store %zu elements\n", approx_size_bytes >> 20, (nMaxCacheSize * 2) >> 20, num_elems); return true; |