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| 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 | f727b6ea8f3b42496e21361ddc1af9d7e12582ad (patch) | |
| tree | 927ccb3b3ffc8a63fe63ef35c1a7b030c041222e /src/backend/access/transam/xact.c | |
| parent | 72918ea86cb9308dd4748b4e269e3a53917cbdca (diff) | |
| download | postgresql-f727b6ea8f3b42496e21361ddc1af9d7e12582ad.tar.gz postgresql-f727b6ea8f3b42496e21361ddc1af9d7e12582ad.zip | |
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/xact.c')
| -rw-r--r-- | src/backend/access/transam/xact.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index a093cd814a1..9c6b87c6ecf 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -5257,8 +5257,9 @@ 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); |