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/utils/time/snapmgr.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/utils/time/snapmgr.c')
| -rw-r--r-- | src/backend/utils/time/snapmgr.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index dca1bc8afca..3037cf478d1 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -536,12 +536,14 @@ SetTransactionSnapshot(Snapshot sourcesnap, VirtualTransactionId *sourcevxid, CurrentSnapshot->xmax = sourcesnap->xmax; CurrentSnapshot->xcnt = sourcesnap->xcnt; Assert(sourcesnap->xcnt <= GetMaxSnapshotXidCount()); - memcpy(CurrentSnapshot->xip, sourcesnap->xip, - sourcesnap->xcnt * sizeof(TransactionId)); + if (sourcesnap->xcnt > 0) + memcpy(CurrentSnapshot->xip, sourcesnap->xip, + sourcesnap->xcnt * sizeof(TransactionId)); CurrentSnapshot->subxcnt = sourcesnap->subxcnt; Assert(sourcesnap->subxcnt <= GetMaxSnapshotSubxidCount()); - memcpy(CurrentSnapshot->subxip, sourcesnap->subxip, - sourcesnap->subxcnt * sizeof(TransactionId)); + if (sourcesnap->subxcnt > 0) + memcpy(CurrentSnapshot->subxip, sourcesnap->subxip, + sourcesnap->subxcnt * sizeof(TransactionId)); CurrentSnapshot->suboverflowed = sourcesnap->suboverflowed; CurrentSnapshot->takenDuringRecovery = sourcesnap->takenDuringRecovery; /* NB: curcid should NOT be copied, it's a local matter */ |