From 03a013360d0262142e2ee68897098310564bff9e Mon Sep 17 00:00:00 2001
From: Simon Marlow <smarlow@meta.com>
Date: Thu, 28 Nov 2024 06:03:44 -0800
Subject: [PATCH] Fix a possible ownership bug

Summary:
I don't know whether this leads to the crash we've seen, but it seems
to be a bug: when we deserialize a set we're adding 8 junk bytes at
the end.

Reviewed By: malanka

Differential Revision: D66573036

fbshipit-source-id: 7c7a22626056204554bfdd49101e11276c52d70a
---
 glean/rocksdb/ownership.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/glean/rocksdb/ownership.cpp b/glean/rocksdb/ownership.cpp
index 07cb02eed..511381f29 100644
--- a/glean/rocksdb/ownership.cpp
+++ b/glean/rocksdb/ownership.cpp
@@ -139,11 +139,12 @@ std::unique_ptr<rts::OwnershipSetIterator> getSetIterator(DatabaseImpl& db) {
         auto usetid = key.trustedNat();
         // EliasFano needs to be able to read 8 bytes past the end of
         // the data, so we have to copy the bytes to add padding.
+        const size_t pad = 8;
         bytes = hs::ffi::clone_array<uint8_t>(
             reinterpret_cast<const uint8_t*>(iter->value().data()),
             iter->value().size(),
-            8);
-        binary::Input val(bytes.get(), bytes.size());
+            pad);
+        binary::Input val(bytes.get(), iter->value().size());
         exp.op = static_cast<SetOp>(val.trustedNat());
         exp.set = deserializeEliasFano(val);
         return std::pair<uint32_t, SetExpr<const OwnerSet*>>(