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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
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5
src/backend/access/transam/clog.c
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@ -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