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Remove dependency to system calls for memory allocation in refint 

Failures in allocations could lead to crashes with NULL pointer
dereferences .  Memory context TopMemoryContext is used instead to keep
alive the plans allocated in the session.  A more specific context could
be used here, but this is left for later.

Reported-by: Jian Zhang
Author: Michael Paquier
Reviewed-by: Tom Lane, Andres Freund
Discussion: https://postgr.es/m/16190-70181c803641c3dc@postgresql.org
This commit is contained in:
Michael Paquier 2020-01-08 10:02:55 +09:00
parent b175bd59fa
commit b0b6196386
1 changed files with 20 additions and 6 deletions
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26
contrib/spi/refint.c
View File

@ -12,6 +12,7 @@
#include "commands/trigger.h"
#include "executor/spi.h"
#include "utils/builtins.h"
#include "utils/memutils.h"
#include "utils/rel.h"
PG_MODULE_MAGIC;
@ -186,12 +187,13 @@ check_primary_key(PG_FUNCTION_ARGS)
/*
* Remember that SPI_prepare places plan in current memory context -
* so, we have to save plan in Top memory context for later use.
* so, we have to save plan in TopMemoryContext for later use.
*/
if (SPI_keepplan(pplan))
/* internal error */
elog(ERROR, "check_primary_key: SPI_keepplan failed");
plan->splan = (SPIPlanPtr *) malloc(sizeof(SPIPlanPtr));
plan->splan = (SPIPlanPtr *) MemoryContextAlloc(TopMemoryContext,
sizeof(SPIPlanPtr));
*(plan->splan) = pplan;
plan->nplans = 1;
}
@ -417,7 +419,8 @@ check_foreign_key(PG_FUNCTION_ARGS)
char sql[8192];
char **args2 = args;
plan->splan = (SPIPlanPtr *) malloc(nrefs * sizeof(SPIPlanPtr));
plan->splan = (SPIPlanPtr *) MemoryContextAlloc(TopMemoryContext,
nrefs * sizeof(SPIPlanPtr));
for (r = 0; r < nrefs; r++)
{
@ -614,6 +617,13 @@ find_plan(char *ident, EPlan **eplan, int *nplans)
{
EPlan *newp;
int i;
MemoryContext oldcontext;
/*
* All allocations done for the plans need to happen in a session-safe
* context.
*/
oldcontext = MemoryContextSwitchTo(TopMemoryContext);
if (*nplans > 0)
{
@ -623,20 +633,24 @@ find_plan(char *ident, EPlan **eplan, int *nplans)
break;
}
if (i != *nplans)
{
MemoryContextSwitchTo(oldcontext);
return (*eplan + i);
*eplan = (EPlan *) realloc(*eplan, (i + 1) * sizeof(EPlan));
}
*eplan = (EPlan *) repalloc(*eplan, (i + 1) * sizeof(EPlan));
newp = *eplan + i;
}
else
{
newp = *eplan = (EPlan *) malloc(sizeof(EPlan));
newp = *eplan = (EPlan *) palloc(sizeof(EPlan));
(*nplans) = i = 0;
}
newp->ident = strdup(ident);
newp->ident = pstrdup(ident);
newp->nplans = 0;
newp->splan = NULL;
(*nplans)++;
MemoryContextSwitchTo(oldcontext);
return newp;
}