[impala] 03/03: IMPALA-8846: Undefined behaviour in RleEncoder::Put

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tarmstrong pushed a commit to branch master
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commit f26a32f85542bfdbceb7306a06327f66dc30294a
Author: Daniel Becker <da...@cloudera.com>
AuthorDate: Fri Aug 9 10:08:55 2019 +0200

    IMPALA-8846: Undefined behaviour in RleEncoder::Put
    
    To test for overflow, we used 'repeat_count_ <=
    std::numeric_limits<int32_t>::max()', but this is always true as
    repeat_count_ is an int. This could have lead to undefined behaviour
    because we increment repeat_count_ afterwards.
    
    Changed the comparison not to allow equality.
    
    Change-Id: I269443d1f1680e672fde7dd88eab5fcb56c65613
    Reviewed-on: http://gerrit.cloudera.org:8080/14042
    Reviewed-by: Impala Public Jenkins <im...@cloudera.com>
    Tested-by: Impala Public Jenkins <im...@cloudera.com>
---
 be/src/util/rle-encoding.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/be/src/util/rle-encoding.h b/be/src/util/rle-encoding.h
index 4da9fd9..4ea3769 100644
--- a/be/src/util/rle-encoding.h
+++ b/be/src/util/rle-encoding.h
@@ -344,7 +344,7 @@ inline bool RleEncoder::Put(uint64_t value) {
   if (UNLIKELY(buffer_full_)) return false;
 
   if (LIKELY(current_value_ == value
-      && repeat_count_ <= std::numeric_limits<int32_t>::max())) {
+      && repeat_count_ < std::numeric_limits<int32_t>::max())) {
     ++repeat_count_;
     if (repeat_count_ > 8) {
       // This is just a continuation of the current run, no need to buffer the