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Clean up assorted failures under clang's -fsanitize=undefined checks.

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Most of these are cases where we could call memcpy() or other libc
functions with a NULL pointer and a zero count, which is forbidden
by POSIX even though every production version of libc allows it.
We've fixed such things before in a piecemeal way, but apparently
never made an effort to try to get them all.  I don't claim that
this patch does so either, but it gets every failure I observe in
check-world, using clang 12.0.1 on current RHEL8.

numeric.c has a different issue that the sanitizer doesn't like:
"ln(-1.0)" will compute log10(0) and then try to assign the
resulting -Inf to an integer variable.  We don't actually use the
result in such a case, so there's no live bug.

Back-patch to all supported branches, with the idea that we might
start running a buildfarm member that tests this case.  This includes
back-patching c1132aae3 (Check the size in COPY_POINTER_FIELD),
which previously silenced some of these issues in copyfuncs.c.

Discussion: https://postgr.es/m/CALNJ-vT9r0DSsAOw9OXVJFxLENoVS_68kJ5x0p44atoYH+H4dg@mail.gmail.com
This commit is contained in:
Tom Lane
2022-03-03 18:13:24 -05:00
parent 62ce0c758d
commit 46ab07ffda
9 changed files with 31 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
src/backend/access/heap/heapam.c
View File

@@ -328,7 +328,7 @@ initscan(HeapScanDesc scan, ScanKey key, bool keep_startblock)
/*
* copy the scan key, if appropriate
*/
if (key != NULL)
if (key != NULL && scan->rs_base.rs_nkeys > 0)
memcpy(scan->rs_base.rs_key, key, scan->rs_base.rs_nkeys * sizeof(ScanKeyData));
/*

4
src/backend/access/heap/heapam_visibility.c
View File

@@ -1564,8 +1564,8 @@ HeapTupleHeaderIsOnlyLocked(HeapTupleHeader tuple)
static bool
TransactionIdInArray(TransactionId xid, TransactionId *xip, Size num)
{
return bsearch(&xid, xip, num,
sizeof(TransactionId), xidComparator) != NULL;
return num > 0 &&
bsearch(&xid, xip, num, sizeof(TransactionId), xidComparator) != NULL;
}
/*

5
src/backend/access/transam/clog.c
View File

@@ -297,8 +297,9 @@ TransactionIdSetPageStatus(TransactionId xid, int nsubxids,
if (all_xact_same_page && xid == MyProc->xid &&
nsubxids <= THRESHOLD_SUBTRANS_CLOG_OPT &&
nsubxids == MyProc->subxidStatus.count &&
memcmp(subxids, MyProc->subxids.xids,
nsubxids * sizeof(TransactionId)) == 0)
(nsubxids == 0 ||
memcmp(subxids, MyProc->subxids.xids,
nsubxids * sizeof(TransactionId)) == 0))
{
/*
* If we can immediately acquire XactSLRULock, we update the status of

5
src/backend/access/transam/xact.c
View File

@@ -5353,8 +5353,9 @@ SerializeTransactionState(Size maxsize, char *start_address)
{
if (FullTransactionIdIsValid(s->fullTransactionId))
workspace[i++] = XidFromFullTransactionId(s->fullTransactionId);
memcpy(&workspace[i], s->childXids,
s->nChildXids * sizeof(TransactionId));
if (s->nChildXids > 0)
memcpy(&workspace[i], s->childXids,
s->nChildXids * sizeof(TransactionId));
i += s->nChildXids;
}
Assert(i == nxids);