Prevent a corrupt database from causing a CPU stack overflow in PRAGMA

integrity_check.  Report the excess btree depth instead.
[bugs:/info/2026-08-18T10:33:10Z|Bug 2026-08-18T10:33:10Z].

FossilOrigin-Name: afd9f401c4dd99be3df2bb5681d8e5c73f9268282392185a2b40c91407732788

manifest

@@ -1,5 +1,5 @@
-C Use\sa\stypecast\sto\sfix\sa\spossible\sinteger\soverflow\sin\sthe\s\n(unsupported)\sext/misc/compress.c\sextension.\n[bugs:/info/2026-08-18T09:33:57Z|Bug\s2026-08-18T09:33:57Z].
-D 2026-08-18T10:33:46.805
+C Prevent\sa\scorrupt\sdatabase\sfrom\scausing\sa\sCPU\sstack\soverflow\sin\sPRAGMA\nintegrity_check.\s\sReport\sthe\sexcess\sbtree\sdepth\sinstead.\n[bugs:/info/2026-08-18T10:33:10Z|Bug\s2026-08-18T10:33:10Z].
+D 2026-08-18T13:07:33.751
 F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@ -683,9 +683,9 @@ F src/auth.c b5ece4e1edccad082c0332fa0087df225473bae0feea9269f824312201377185
 F src/backup.c f6a1490f4ef86cca51f0f93158bbc140b5822406e0c50ec61731e3fcdc1242a2
 F src/bitvec.c e242d4496774dfc88fa278177dd23b607dce369ccafb3f61b41638eea2c9b399
 F src/btmutex.c 30dada73a819a1ef5b7583786370dce1842e12e1ad941e4d05ac29695528daea
-F src/btree.c c99c5e3758ee506de6ae60c12e14ba3ab1ed0336b80a7795b60c7d807dd8189c
+F src/btree.c b95c69c7057f652ef654c421cdafdc9a847aeed56af153e5e86cf115ad3d9552
 F src/btree.h 2ee0ddfdf4f8530ad1d46afffd7da21a0e243bfab10973011ac6f6b7fb4109a1
-F src/btreeInt.h 1e4a7d04e809e98abc39654b6089c60d749a724598041ff553b392a3277e9b98
+F src/btreeInt.h df956bca48cd49d2a38886bc3b02045c039e8a16353f86fccd116c6487f79d82
 F src/build.c 6d55fcda11273ae382e1bcf9695468ca0c05547a2e2f6f09d64f30cb64f4400e
 F src/callback.c 3605bbf02bd7ed46c79cd48346db4a32fc51d67624400539c0532f4eead804ad
 F src/carray.c 22879bbd9e14fc4868f223b0d49bcdbbda4616c89f1519ec6a5e64b98a4137b1
@@ -2219,8 +2219,8 @@ F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee
 F tool/warnings.sh a554d13f6e5cf3760f041b87939e3d616ec6961859c3245e8ef701d1eafc2ca2
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
 F tool/winmain.c 00c8fb88e365c9017db14c73d3c78af62194d9644feaf60e220ab0f411f3604c
-P 003ed951d85416da97f5cabf96d89b974279bd8ef2433ae1987bdedad38a4b90
-R 6b4b0611ce6cfddda2c13339b3012cc7
+P d0f1f683b94f90ba111509ec1c108a73388579c870aa740379b28cbb00a2827b
+R 078fdc6847a45d090bf8ffdf7137931c
 U drh
-Z 9d95fe9ae223fd37fc65c0468d36d136
+Z e4c435b7060d23716d96d9531cadefbf
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-d0f1f683b94f90ba111509ec1c108a73388579c870aa740379b28cbb00a2827b
+afd9f401c4dd99be3df2bb5681d8e5c73f9268282392185a2b40c91407732788

src/btree.c

@@ -10919,19 +10919,24 @@ static int checkTreePage(
   /* Check that the page exists
   */
   checkProgress(pCheck);
-  if( pCheck->mxErr==0 ) goto end_of_check;
+  if( pCheck->mxErr==0 ) return 0;
   pBt = pCheck->pBt;
   usableSize = pBt->usableSize;
   if( iPage==0 ) return 0;
   if( checkRef(pCheck, iPage) ) return 0;
   pCheck->zPfx = "Tree %u page %u: ";
   pCheck->v1 = iPage;
+  pCheck->nAbove++;
   if( (rc = btreeGetPage(pBt, iPage, &pPage, 0))!=0 ){
     checkAppendMsg(pCheck,
        "unable to get the page. error code=%d", rc);
     if( rc==SQLITE_IOERR_NOMEM ) pCheck->rc = SQLITE_NOMEM;
     goto end_of_check;
   }
+  if( pCheck->nAbove > BTCURSOR_MAX_DEPTH ){
+    checkAppendMsg(pCheck,"btree depth exceeds %d",BTCURSOR_MAX_DEPTH);
+    goto end_of_check;
+  }
 
   /* Clear MemPage.isInit to make sure the corruption detection code in
   ** btreeInitPage() is executed.  */
@@ -11151,6 +11156,7 @@ end_of_check:
   pCheck->zPfx = saved_zPfx;
   pCheck->v1 = saved_v1;
   pCheck->v2 = saved_v2;
+  pCheck->nAbove--;
   return depth+1;
 }
 #endif /* SQLITE_OMIT_INTEGRITY_CHECK */
@@ -11283,7 +11289,9 @@ int sqlite3BtreeIntegrityCheck(
       }
 #endif
       sCheck.v0 = aRoot[i];
+      assert( sCheck.nAbove==0 );
       checkTreePage(&sCheck, aRoot[i], &notUsed, LARGEST_INT64);
+      assert( sCheck.nAbove==0 );
     }
     sqlite3MemSetArrayInt64(aCnt, i, sCheck.nRow);
   }

src/btreeInt.h

@@ -709,6 +709,7 @@ struct IntegrityCk {
   int nErr;         /* Number of messages written to zErrMsg so far */
   int rc;           /* SQLITE_OK, SQLITE_NOMEM, or SQLITE_INTERRUPT */
   u32 nStep;        /* Number of steps into the integrity_check process */
+  u8 nAbove;        /* Current btree recursion depth */
   const char *zPfx; /* Error message prefix */
   Pgno v0;          /* Value for first %u substitution in zPfx (root page) */
   Pgno v1;          /* Value for second %u substitution in zPfx (current pg) */