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Fix reads into bad memory in readwritesplit

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The candidate selection code used default values that would cause reads
past buffers. The code could also dereference the end iterator which
causes undefined behavior.
This commit is contained in:
Markus Mäkelä
2019-03-13 19:35:32 +02:00
parent b537176248
commit e5edb5c78f
1 changed files with 7 additions and 2 deletions
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9
server/modules/routing/readwritesplit/rwsplit_select_backends.cc
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@ -222,7 +222,7 @@ SRWBackendVector::iterator find_best_backend(SRWBackendVector& backends,
bool masters_accepts_reads) bool masters_accepts_reads)
{ {
// Group backends by priority. The set of highest priority backends will then compete. // Group backends by priority. The set of highest priority backends will then compete.
int best_priority {INT_MAX}; // low numbers are high priority int best_priority {2}; // low numbers are high priority
for (auto& psBackend : backends) for (auto& psBackend : backends)
{ {
@ -252,7 +252,12 @@ SRWBackendVector::iterator find_best_backend(SRWBackendVector& backends,
} }
auto best = select(priority_map[best_priority]); auto best = select(priority_map[best_priority]);
auto rval = std::find(backends.begin(), backends.end(), *best); auto rval = backends.end();
if (best != priority_map[best_priority].end())
{
rval = std::find(backends.begin(), backends.end(), *best);
}
for (auto& a : priority_map) for (auto& a : priority_map)
{ {