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Commitd40d827

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Robustify find_base_rel and find_base_rel_ignore_join
Improve find_base_rel() and find_base_rel_ignore_join() so that theyraise an ERROR if they ever receive a negative relid value innon-cassert builds. If either of these functions had ever received anegative relid then they'd have attempted to access memory that does notbelong to simple_rel_array.Because no evidence has been presented of actual cases where bugs havecaused this to happen, here we take a lightweight approach to checkingfor negative values and simply cast both values to uint32 beforeperforming the comparison. This will cause any negative relids to beseen as greater than simple_rel_array_size which will ERROR rather thanattempt to access a negative simple_rel_array element. Obviously, therun-time error is better than a crash, so it makes sense to protectagainst this, especially when it can be done without adding anyadditional run-time overhead.There is a slight change here if the functions are ever called with arelid of 0. This will pass the bounds check, but that array entryshould be NULL (along with the corresponding simple_rte_array entry), sowon't pass the "if (rel)" condition and still fall through and raise anERROR.Author: Ranier VilelaReviewed-by: Ashutosh Bapat, David RowleyDiscussion:https://postgr.es/m/CAEudQArQSghBu2gLojg4o_tnHj_x2HcS%3D%2BwewL3NJS8z0VnK%2Bg%40mail.gmail.com
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‎src/backend/optimizer/util/relnode.c

Lines changed: 4 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -406,9 +406,8 @@ find_base_rel(PlannerInfo *root, int relid)
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{
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RelOptInfo*rel;
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Assert(relid>0);
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if (relid<root->simple_rel_array_size)
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/* use an unsigned comparison to prevent negative array element access */
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if ((uint32)relid< (uint32)root->simple_rel_array_size)
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{
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rel=root->simple_rel_array[relid];
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if (rel)
@@ -432,9 +431,8 @@ find_base_rel(PlannerInfo *root, int relid)
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RelOptInfo*
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find_base_rel_ignore_join(PlannerInfo*root,intrelid)
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{
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Assert(relid>0);
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if (relid<root->simple_rel_array_size)
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/* use an unsigned comparison to prevent negative array element access */
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if ((uint32)relid< (uint32)root->simple_rel_array_size)
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{
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RelOptInfo*rel;
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RangeTblEntry*rte;

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