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 4205e9c3effe51e710525fd631861171f7ef476f..2099ce2a7a5c175e41c98463bcda7209719b4540 100644 (file)
--- a/contrib/pgcrypto/px.c
+++ b/contrib/pgcrypto/px.c
@@ -200,7 +200,7 @@ 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 9e258f918e50a2cb7ce75dc0410a5b62b7693a53..763dc07361e19c2aaaadcd70f19ca28945a3b0df 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 d3c57cd16a836c6ec87278aaec79b9b92cc7c99b..20d82cad4b6ebfdb3a7a511ca90d4b3a2fdfe829 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 3ea16a270a8c641b2096ba98e5d8a11d7dbf7b38..8575f1cb8e658854a37af43cca25912343487d8e 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 ca6f6d57d3663bf2d7c04a52e51a42da3c1b3909..514044f3db7c472bb3ba0def8b79564a81780e27 100644 (file)
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -5305,8 +5305,9 @@ 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/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index f0fa2e23375187ab20ebb2f786aa41888e3cc4d2..a106a2cdf182ac073815e97532bfbf36b3fec092 100644 (file)
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -57,8 +57,11 @@
 #define COPY_POINTER_FIELD(fldname, sz) \
        do { \
                Size    _size = (sz); \
-               newnode->fldname = palloc(_size); \
-               memcpy(newnode->fldname, from->fldname, _size); \
+               if (_size > 0) \
+               { \
+                       newnode->fldname = palloc(_size); \
+                       memcpy(newnode->fldname, from->fldname, _size); \
+               } \
        } while (0)
 
 /* Copy a parse location field (for Copy, this is same as scalar case) */
@@ -296,12 +299,9 @@ _copyRecursiveUnion(const RecursiveUnion *from)
         */
        COPY_SCALAR_FIELD(wtParam);
        COPY_SCALAR_FIELD(numCols);
-       if (from->numCols > 0)
-       {
-               COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
-               COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
-               COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
-       }
+       COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
+       COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+       COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
        COPY_SCALAR_FIELD(numGroups);
 
        return newnode;
@@ -897,13 +897,10 @@ _copyMergeJoin(const MergeJoin *from)
        COPY_SCALAR_FIELD(skip_mark_restore);
        COPY_NODE_FIELD(mergeclauses);
        numCols = list_length(from->mergeclauses);
-       if (numCols > 0)
-       {
-               COPY_POINTER_FIELD(mergeFamilies, numCols * sizeof(Oid));
-               COPY_POINTER_FIELD(mergeCollations, numCols * sizeof(Oid));
-               COPY_POINTER_FIELD(mergeStrategies, numCols * sizeof(int));
-               COPY_POINTER_FIELD(mergeNullsFirst, numCols * sizeof(bool));
-       }
+       COPY_POINTER_FIELD(mergeFamilies, numCols * sizeof(Oid));
+       COPY_POINTER_FIELD(mergeCollations, numCols * sizeof(Oid));
+       COPY_POINTER_FIELD(mergeStrategies, numCols * sizeof(int));
+       COPY_POINTER_FIELD(mergeNullsFirst, numCols * sizeof(bool));
 
        return newnode;
 }
@@ -1067,12 +1064,9 @@ _copyAgg(const Agg *from)
        COPY_SCALAR_FIELD(aggstrategy);
        COPY_SCALAR_FIELD(aggsplit);
        COPY_SCALAR_FIELD(numCols);
-       if (from->numCols > 0)
-       {
-               COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
-               COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
-               COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
-       }
+       COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
+       COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+       COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
        COPY_SCALAR_FIELD(numGroups);
        COPY_SCALAR_FIELD(transitionSpace);
        COPY_BITMAPSET_FIELD(aggParams);
@@ -1094,19 +1088,13 @@ _copyWindowAgg(const WindowAgg *from)
 
        COPY_SCALAR_FIELD(winref);
        COPY_SCALAR_FIELD(partNumCols);
-       if (from->partNumCols > 0)
-       {
-               COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
-               COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
-               COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
-       }
+       COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
+       COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
+       COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
        COPY_SCALAR_FIELD(ordNumCols);
-       if (from->ordNumCols > 0)
-       {
-               COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
-               COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
-               COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
-       }
+       COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
+       COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
+       COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
        COPY_SCALAR_FIELD(frameOptions);
        COPY_NODE_FIELD(startOffset);
        COPY_NODE_FIELD(endOffset);

diff --git a/src/backend/storage/ipc/shm_mq.c b/src/backend/storage/ipc/shm_mq.c
index 8a46962f939a35a0e2e26aaba939b085b3b95f9f..3240af4872af3bbee80b820548c5079862e832d5 100644 (file)
--- a/src/backend/storage/ipc/shm_mq.c
+++ b/src/backend/storage/ipc/shm_mq.c
@@ -748,8 +748,11 @@ 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 4ca13f4f4775e5b002db66f18eff923fecb17b0c..e78e0b92479718b429158aa42abe8b11ec73d4e3 100644 (file)
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -9868,12 +9868,20 @@ 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 dca1bc8afca6e4f52e1bf3a3fda7c7f00fca4a1a..3037cf478d1dece60e8f8f065b04c0f4a34c6c20 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 d48fcc4a0328de76bd6b13d6313805e54eca118f..2d0f78b8a2d5982a97268638e197c0d7f1deefd7 100644 (file)
--- a/src/fe_utils/print.c
+++ b/src/fe_utils/print.c
@@ -896,7 +896,8 @@ 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)