Fix a bug causing the session module to dereference a NULL pointer when applying a corrupt changeset.

FossilOrigin-Name: c813d9b777bedd58005b53d38fa3c235ca56bd57b76424cf9238c01a977a4b3d

ext/session/session9.test

@@ -324,5 +324,47 @@ do_test 6.3.2 { sqlite3_errcode db2 } {SQLITE_ERROR}
 do_test 6.4 {
   catchsql { INSERT INTO c1 VALUES(100, 200) } db2
 } {1 {no such table: main.p1}}
+db2 close
+
+#-------------------------------------------------------------------------
+reset_db
+
+do_execsql_test 7.0 {
+  PRAGMA trusted_schema=OFF;
+  PRAGMA foreign_keys=ON;
+  CREATE TABLE t1(a INTEGER PRIMARY KEY, b, c, d);
+  CREATE TABLE t2(e TEXT PRIMARY KEY NOT NULL, f, g);
+  CREATE TABLE t3(w REAL PRIMARY KEY NOT NULL, x, y);
+  CREATE TABLE t4(z PRIMARY KEY) WITHOUT ROWID;
+  CREATE TABLE tc(a INTEGER, b INTEGER, c BLOB, d TEXT, PRIMARY KEY(a,b));
+  CREATE TABLE wr(a TEXT, b INT, c, PRIMARY KEY(a,b)) WITHOUT ROWID;
+  CREATE TABLE child(x INTEGER PRIMARY KEY, y INTEGER REFERENCES t1(a) ON DELETE CASCADE, z TEXT);
+  INSERT INTO t1 VALUES(1,2,3,4),(2,3.5,'four',x'556677'),(3,NULL,'xyz',15),(4,'bubba',2147483648,0.0);
+  INSERT INTO t1 SELECT a+4,c,d,b FROM t1;
+  INSERT INTO t2 VALUES('x1y',2,3),('x2y','four',x'556677'),('x3y',NULL,'xyz');
+  INSERT INTO t3 VALUES(1.1,'a','b'),(2.2,x'00ff','c');
+  INSERT INTO t4 VALUES('alpha'),('beta'),('gamma');
+  INSERT INTO tc VALUES(1,1,x'0102','one'),(1,2,x'0304','two'),(2,1,x'0506','three');
+  INSERT INTO wr VALUES('a',1,'wa'),('b',2,'wb');
+  INSERT INTO child VALUES(1,1,'c1'),(2,2,'c2');
+}
+
+set C [db one "SELECT unhex('
+      54 0401 0200 0074 6300 1700 0100 0000
+    0000 0000 0101 0000 0000 0069 0001 0402
+    0102 0303 6f6e 6500 0004 2008 40a1 4c0b
+    0d3f 3730 5d92 3f18 f2c9 66a6 4220 a873
+    04cc 5281 ce5c d9d4 dc8b 7003 056f 6e65
+    2d75 1700 0100 0002 5004 0100 0000 6d69
+    7800 1700 0302 6b31 0409 1100
+', ' \n')"]
+
+
+proc conflict_handler {args} { 
+  return "OMIT" 
+}
+do_test 7.1 {
+  list [catch {sqlite3changeset_apply_v2 db $::C conflict_handler} msg] $msg
+} {1 SQLITE_CORRUPT}
 
 finish_test

ext/session/sqlite3session.c

@@ -5044,7 +5044,7 @@ static int sessionApplyOneOp(
     for(i=0; rc==SQLITE_OK && i<nCol; i++){
       sqlite3_value *pOld = sessionChangesetOld(pIter, i);
       sqlite3_value *pNew = sessionChangesetNew(pIter, i);
-      if( p->abPK[i] || (bPatchset==0 && pOld) ){
+      if( pOld && (p->abPK[i] || bPatchset==0) ){
         rc = sessionBindValue(pUp, i*2+2, pOld);
       }
       if( rc==SQLITE_OK && pNew ){

manifest

@@ -1,5 +1,5 @@
-C Check-in\s[0d01c90bd7779192]\swas\sincomplete\sin\sthat\sit\sdid\snot\sremove\nthe\sincorrect\sassert()\sstatement.\s\sFixed\shere.
-D 2026-05-20T11:59:36.200
+C Fix\sa\sbug\scausing\sthe\ssession\smodule\sto\sdereference\sa\sNULL\spointer\swhen\sapplying\sa\scorrupt\schangeset.
+D 2026-05-20T15:29:37.214
 F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@ -538,7 +538,7 @@ F ext/session/session4.test ad0ddaaddb9a99dac433d83fc6674aae2af072b8f57e63a6b3f2
 F ext/session/session5.test 716bc6fafd625ce60dfa62ae128971628c1a1169
 F ext/session/session6.test 35279f2ec45448cd2e24a61688219dc6cf7871757716063acf4a8b5455e1e926
 F ext/session/session8.test 326f3273abf9d5d2d7d559eee8f5994c4ea74a5d935562454605e6607ee29904
-F ext/session/session9.test 0c4a8fbe7a5031f50855f020f3408e1f07fd7859f1daa1629eadcec3422072d6
+F ext/session/session9.test ce2b898aa4caf0e492b57c29cb707224e0a33479e4f019785a81828273143ba5
 F ext/session/sessionA.test 1feeab0b8e03527f08f2f1defb442da25480138f
 F ext/session/sessionB.test c4fb7f8a688787111606e123a555f18ee04f65bb9f2a4bb2aa71d55ce4e6d02c
 F ext/session/sessionC.test de98b5e173fd86c79af0d0541534398d2ea75dc0d5d74a00103eb26151b76959
@@ -572,7 +572,7 @@ F ext/session/sessionrowid.test 85187c2f1b38861a5844868126f69f9ec62223a03449a98a
 F ext/session/sessionsize.test 8fcf4685993c3dbaa46a24183940ab9f5aa9ed0d23e5fb63bfffbdb56134b795
 F ext/session/sessionstat1.test 5e718d5888c0c49bbb33a7a4f816366db85f59f6a4f97544a806421b85dc2dec
 F ext/session/sessionwor.test 6fd9a2256442cebde5b2284936ae9e0d54bde692d0f5fd009ecef8511f4cf3fc
-F ext/session/sqlite3session.c e26a3c4352387809f505acd2186d7f6b024260503402a136e0fe7b36a9a4d60c
+F ext/session/sqlite3session.c 3914203a4970a96ccdc6f5b5d0afd09df29da87aed7723363c7bb648ea906c7b
 F ext/session/sqlite3session.h 063e7bf7be2fff874456f452a224b5b3013b25682d108933b0351c93a1279b9c
 F ext/session/test_session.c 2a02a68b522e2f3d4a64b2a4733af54b0f3e500769aeccd5bcbdd440103db069
 F ext/wasm/GNUmakefile 68c750f173106d9d63f12c1edf1256c6f4bad9894b155da5db64322f4912de4b
@@ -2198,9 +2198,9 @@ F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee
 F tool/warnings.sh a554d13f6e5cf3760f041b87939e3d616ec6961859c3245e8ef701d1eafc2ca2
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
 F tool/winmain.c 00c8fb88e365c9017db14c73d3c78af62194d9644feaf60e220ab0f411f3604c
-P 15fb7ffe4be49d5242c47bef1b3cad5c923cd7f500896058db4dd257bc7b3924
-Q +c19bacca13f699953bbf50afb867035a94080b8a48111cf3d87bced880a3e620
-R aa69b29016d037d8f37b2524d2801f84
+P 2e9bb51ae951c421f7e5ed8e55fd6dca8b7d4b8543fd3ba3a9e9f017592c028b
+Q +e807d4e3798efd532b3d78d1dfe513ed4fbd3cb793dd0ae5c30cae6031422b10
+R b59d4271c87ada451c68bee193711c01
 U drh
-Z 4751dab5d943960dd85a9fde897a8e9e
+Z c4f77c701d91530fc2ef636803bfa763
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-2e9bb51ae951c421f7e5ed8e55fd6dca8b7d4b8543fd3ba3a9e9f017592c028b
+c813d9b777bedd58005b53d38fa3c235ca56bd57b76424cf9238c01a977a4b3d