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| author | Melanie Plageman <melanieplageman@gmail.com> | 2024-12-20 09:41:41 -0500 |
|---|---|---|
| committer | Melanie Plageman <melanieplageman@gmail.com> | 2024-12-20 09:43:44 -0500 |
| commit | 94bb6c4410d81ccc019bb60d8aedb73dbc85df76 (patch) | |
| tree | 5b713e145c35bc3d094a6ac011b2ceed89f20f15 /src/backend/access/heap/heapam_handler.c | |
| parent | 38c579b08988e6f1a5bd74241d0a1001421d8015 (diff) | |
| download | postgresql-94bb6c4410d81ccc019bb60d8aedb73dbc85df76.tar.gz postgresql-94bb6c4410d81ccc019bb60d8aedb73dbc85df76.zip | |
Fix overflow danger in SampleHeapTupleVisible(), take 2
28328ec87b45725 addressed one overflow danger in
SampleHeapTupleVisible() but introduced another, albeit a less likely
one. Modify the binary search code to remove this danger.
Reported-by: Richard Guo
Reviewed-by: Richard Guo, Ranier Vilela
Discussion: https://postgr.es/m/CAMbWs4_bE%2BNscChbKWzw6HZOipCUyXfA5133qvoXQ654D3B2gQ%40mail.gmail.com
Diffstat (limited to 'src/backend/access/heap/heapam_handler.c')
| -rw-r--r-- | src/backend/access/heap/heapam_handler.c | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c index 9f17baea5d6..53f572f384b 100644 --- a/src/backend/access/heap/heapam_handler.c +++ b/src/backend/access/heap/heapam_handler.c @@ -2574,11 +2574,8 @@ SampleHeapTupleVisible(TableScanDesc scan, Buffer buffer, if (scan->rs_flags & SO_ALLOW_PAGEMODE) { - uint32 start, - end; - - if (hscan->rs_ntuples == 0) - return false; + uint32 start = 0, + end = hscan->rs_ntuples; /* * In pageatatime mode, heap_prepare_pagescan() already did visibility @@ -2589,18 +2586,15 @@ SampleHeapTupleVisible(TableScanDesc scan, Buffer buffer, * in increasing order, but it's not clear that there would be enough * gain to justify the restriction. */ - start = 0; - end = hscan->rs_ntuples - 1; - - while (start <= end) + while (start < end) { - uint32 mid = (start + end) / 2; + uint32 mid = start + (end - start) / 2; OffsetNumber curoffset = hscan->rs_vistuples[mid]; if (tupoffset == curoffset) return true; else if (tupoffset < curoffset) - end = mid - 1; + end = mid; else start = mid + 1; } |