diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2022-03-03 18:13:24 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2022-03-03 18:13:24 -0500 |
| commit | b0bc196e52e606fe0116fb63da20f57fb577745b (patch) | |
| tree | 99436db14ec4c33b4953df3fb3a1761cfe75107e /src/backend/access/transam/clog.c | |
| parent | 2a1f84636dc335a3edf53a8361ae44bb2ae00093 (diff) | |
Clean up assorted failures under clang's -fsanitize=undefined checks.
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
Diffstat (limited to 'src/backend/access/transam/clog.c')
| -rw-r--r-- | src/backend/access/transam/clog.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c index 3ea16a270a8..8575f1cb8e6 100644 --- a/src/backend/access/transam/clog.c +++ b/src/backend/access/transam/clog.c @@ -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 |