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

diff --git a/contrib/pgcrypto/px.c b/contrib/pgcrypto/px.c
index 75e2426e9fd705565b6fbf5445900278e2c4bc5e..0010addaf7d0371f6bc7449745dba45fefe9c325 100644 (file)
--- a/contrib/pgcrypto/px.c
+++ b/contrib/pgcrypto/px.c
@@ -198,7 +198,7 @@ combo_init(PX_Combo *cx, const uint8 *key, unsigned klen,
        ivbuf = palloc0(ivs);
        if (ivlen > ivs)
            memcpy(ivbuf, iv, ivs);
-       else
+       else if (ivlen > 0)
            memcpy(ivbuf, iv, ivlen);
    }
 

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 59d43e2ba92c97987c948b0a7c0f8ffb83fea6cc..4e6aeba31542f12b16298f67bcfaa7039e18dc51 100644 (file)
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -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));
 
    /*

diff --git a/src/backend/access/heap/heapam_visibility.c b/src/backend/access/heap/heapam_visibility.c
index ceadac70d57447c5991c00b17c8e827198108430..ff0b8a688dec790ce1206d9442e625f8e6b7f4de 100644 (file)
--- a/src/backend/access/heap/heapam_visibility.c
+++ b/src/backend/access/heap/heapam_visibility.c
@@ -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;
 }
 
 /*

diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index de787c3d375b56039e5e2c38e2cbaf60c804281f..3d9088a7048b5415dd23f34123c3e20d39be96e4 100644 (file)
--- 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

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index adf763a8ea4415c810d0cae059c13394aa4d1ac6..8964ddf3ebf9b70b1fa6c79e6d8022b1392b7838 100644 (file)
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -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);

diff --git a/src/backend/storage/ipc/shm_mq.c b/src/backend/storage/ipc/shm_mq.c
index 45b0dfc06203d98b71a852f5cafcb285f107db0e..603cf9b0fa7ec4083f7aec247dd85ec3a87741f5 100644 (file)
--- a/src/backend/storage/ipc/shm_mq.c
+++ b/src/backend/storage/ipc/shm_mq.c
@@ -773,8 +773,11 @@ shm_mq_receive(shm_mq_handle *mqh, Size *nbytesp, void **datap, bool nowait)
 
        /* Copy as much as we can. */
        Assert(mqh->mqh_partial_bytes + rb <= nbytes);
-       memcpy(&mqh->mqh_buffer[mqh->mqh_partial_bytes], rawdata, rb);
-       mqh->mqh_partial_bytes += rb;
+       if (rb > 0)
+       {
+           memcpy(&mqh->mqh_buffer[mqh->mqh_partial_bytes], rawdata, rb);
+           mqh->mqh_partial_bytes += rb;
+       }
 
        /*
         * Update count of bytes that can be consumed, accounting for

diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 975d7dcf47638332a061e8be285b969046dbceac..45547f6ae7f3f0b3b3ba69898234f0cf3f8d0021 100644 (file)
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -10048,12 +10048,20 @@ exp_var(const NumericVar *arg, NumericVar *result, int rscale)
  *
  * Essentially, we're approximating log10(abs(ln(var))).  This is used to
  * determine the appropriate rscale when computing natural logarithms.
+ *
+ * Note: many callers call this before range-checking the input.  Therefore,
+ * we must be robust against values that are invalid to apply ln() to.
+ * We don't wish to throw an error here, so just return zero in such cases.
  */
 static int
 estimate_ln_dweight(const NumericVar *var)
 {
    int         ln_dweight;
 
+   /* Caller should fail on ln(negative), but for the moment return zero */
+   if (var->sign != NUMERIC_POS)
+       return 0;
+
    if (cmp_var(var, &const_zero_point_nine) >= 0 &&
        cmp_var(var, &const_one_point_one) <= 0)
    {

diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index a0b81bf1549b5ae255f9407043adbb2c3be9e5d2..a0be0c411a340580255c1c2097c511cd8c0e6bbd 100644 (file)
--- 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 */

diff --git a/src/fe_utils/print.c b/src/fe_utils/print.c
index 2c8e58ebf5cb5acaf80141e7187f5f8300741823..dcdb2e0d0cb4af4306e5ab3a943c7e552f12e1c5 100644 (file)
--- a/src/fe_utils/print.c
+++ b/src/fe_utils/print.c
@@ -966,7 +966,8 @@ print_aligned_text(const printTableContent *cont, FILE *fout, bool is_pager)
 
            more_col_wrapping = col_count;
            curr_nl_line = 0;
-           memset(header_done, false, col_count * sizeof(bool));
+           if (col_count > 0)
+               memset(header_done, false, col_count * sizeof(bool));
            while (more_col_wrapping)
            {
                if (opt_border == 2)