weaselab/conflict-set
1
Fork 1
Code Issues 5 Pull Requests Actions 1 Packages Releases 13 Activity

Avoid reading uninitialized end.p for point writes/reads

Browse Source 
For point writes and point reads (end.len == 0), end.p is not part of
the API contract and callers may leave it uninitialized -- both the C
and C++ API smoke tests and the fuzz test driver do so.  However,
insertPointWritesOrSorted and check::Job::init unconditionally built a
TrivialSpan from end.p, reading the uninitialized pointer even though
it is never used for point operations.

Move the end span construction into the range-write/range-read branches
so end.p is only read when end.len > 0.  This is semantically identical
but removes the uninitialized reads that MemorySanitizer reports.
This commit is contained in:
weaselbot
2026-07-22 18:48:46 -04:00
parent 0510f01fe1
commit 321a23f1dc
1 changed files with 3 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
ConflictSet.cpp
+3 -4
View File
@@ -3864,11 +3864,10 @@ PRESERVE_NONE void right_side_iter(Job *job, Context *context) {
void Job::init(const ConflictSet::ReadRange *read, ConflictSet::Result *result,
Node *root, int64_t oldestVersionFullPrecision) {
auto begin = TrivialSpan(read->begin.p, read->begin.len);
auto end = TrivialSpan(read->end.p, read->end.len);
if (read->readVersion < oldestVersionFullPrecision) [[unlikely]] {
*result = ConflictSet::TooOld;
continuation = complete;
} else if (end.size() == 0) {
} else if (read->end.len == 0) {
this->begin = begin;
this->n = root;
this->readVersion = InternalVersionT(read->readVersion);
@@ -3876,7 +3875,7 @@ void Job::init(const ConflictSet::ReadRange *read, ConflictSet::Result *result,
continuation = check::point_read_state_machine::begin;
} else {
this->begin = begin;
this->end = end;
this->end = TrivialSpan(read->end.p, read->end.len);
this->n = root;
this->readVersion = InternalVersionT(read->readVersion);
this->result = result;
@@ -5046,8 +5045,8 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
for (int i = 0; i < count; ++i) {
const auto &w = writes[i];
auto begin = TrivialSpan(w.begin.p, w.begin.len);
auto end = TrivialSpan(w.end.p, w.end.len);
if (w.end.len > 0) {
auto end = TrivialSpan(w.end.p, w.end.len);
addWriteRange(rootParent->children[0], begin, end,
InternalVersionT(writeVersion), &writeContext);
} else {