windows-dnlc-corruption-20050517

It has been noticed that on startup there may be corruption of the
dnlc freelist.  In particular, some items on the list are actually
in use.  This patch will cause the dnlc to be purged if corruption
of the freelist is detected.  It also makes changes to ensure that
items placed onto the freelist are in fact cleaned to prevent confusion.

The purge function is corrected to set that magic field to the correct
value.

The validation function is fixed to not CloseHandle the same handle
twice.

diff --git a/src/WINNT/afsd/cm_dnlc.c b/src/WINNT/afsd/cm_dnlc.c
index eced524..47bbd75 100644 (file)
--- a/src/WINNT/afsd/cm_dnlc.c
+++ b/src/WINNT/afsd/cm_dnlc.c
@@ -54,6 +54,7 @@ static int cm_debugDnlc = 0;  /* debug dnlc */
 #define dnlcNotify(x,debug)
 #endif /* !DJGPP */
 
+/* Must be called with cm_dnlcLock write locked */
 static cm_nc_t * 
 GetMeAnEntry() 
 {
@@ -332,8 +333,8 @@ RemoveEntry (tnc, key)
        tnc->next->prev = tnc->prev;
     }
 
-    tnc->prev = (cm_nc_t *) 0; /* everything not in hash table has 0 prev */
-    tnc->key = 0; /* just for safety's sake */
+    memset(tnc, 0, sizeof(cm_nc_t));
+    tnc->magic = CM_DNLC_MAGIC;
     return 0;    /* success */
 }
 
@@ -368,7 +369,6 @@ cm_dnlcRemove ( adp, aname)
        if ( (tnc->dirp == adp) && (tnc->key == key) 
                        && !strcmp(tnc->name,aname) )
        {
-           tnc->dirp = (cm_scache_t *) 0; /* now it won't match anything */
            tmp = tnc->next;
            error = RemoveEntry(tnc, skey);
            if ( error )
@@ -376,7 +376,7 @@ cm_dnlcRemove ( adp, aname)
 
            tnc->next = cm_data.ncfreelist; /* insert entry into freelist */
            cm_data.ncfreelist = tnc;
-           found = 1;          /* found atleast one entry */
+           found = 1;          /* found at least one entry */
 
            tnc = tmp;          /* continue down the linked list */
        }
@@ -426,13 +426,16 @@ cm_dnlcPurgedp (adp)
     {
        if (cm_data.nameCache[i].dirp == adp ) 
        {
-           cm_data.nameCache[i].dirp = cm_data.nameCache[i].vp = (cm_scache_t *) 0;
-           if (cm_data.nameCache[i].prev && !err) 
-           {
-               err = RemoveEntry(&cm_data.nameCache[i], cm_data.nameCache[i].key & (NHSIZE-1));
-               cm_data.nameCache[i].next = cm_data.ncfreelist;
-               cm_data.ncfreelist = &cm_data.nameCache[i];
-           }
+           if (cm_data.nameCache[i].prev) {
+                err = RemoveEntry(&cm_data.nameCache[i], cm_data.nameCache[i].key & (NHSIZE-1));
+                if (!err)
+                {
+                    cm_data.nameCache[i].next = cm_data.ncfreelist;
+                    cm_data.ncfreelist = &cm_data.nameCache[i];
+                }
+           } else {
+                cm_data.nameCache[i].dirp = cm_data.nameCache[i].vp = (cm_scache_t *) 0;
+            }
        }
     }
     lock_ReleaseWrite(&cm_dnlcLock);
@@ -461,15 +464,16 @@ cm_dnlcPurgevp ( avc )
     {
        if (cm_data.nameCache[i].vp == avc) 
        {
-           cm_data.nameCache[i].dirp = cm_data.nameCache[i].vp = (cm_scache_t *) 0;
-           /* can't simply break; because of hard links -- might be two */
-           /* different entries with same vnode */ 
-           if (!err && cm_data.nameCache[i].prev) 
-           {
-               err=RemoveEntry(&cm_data.nameCache[i], cm_data.nameCache[i].key & (NHSIZE-1));
-               cm_data.nameCache[i].next = cm_data.ncfreelist;
-               cm_data.ncfreelist = &cm_data.nameCache[i];
-           }
+           if (cm_data.nameCache[i].prev) {
+                err = RemoveEntry(&cm_data.nameCache[i], cm_data.nameCache[i].key & (NHSIZE-1));
+                if (!err)
+                {
+                    cm_data.nameCache[i].next = cm_data.ncfreelist;
+                    cm_data.ncfreelist = &cm_data.nameCache[i];
+                }
+           } else {
+                cm_data.nameCache[i].dirp = cm_data.nameCache[i].vp = (cm_scache_t *) 0;
+            }
        }
     }
     lock_ReleaseWrite(&cm_dnlcLock);
@@ -494,10 +498,11 @@ void cm_dnlcPurge(void)
     cm_data.ncfreelist = (cm_nc_t *) 0;
     memset (cm_data.nameCache, 0, sizeof(cm_nc_t) * NCSIZE);
     memset (cm_data.nameHash, 0, sizeof(cm_nc_t *) * NHSIZE);
-    for (i=0; i<NCSIZE; i++) 
+    for (i=0; i<NCSIZE; i++)
     {
-       cm_data.nameCache[i].next = cm_data.ncfreelist;
-       cm_data.ncfreelist = &cm_data.nameCache[i];
+        cm_data.nameCache[i].magic = CM_DNLC_MAGIC;
+        cm_data.nameCache[i].next = cm_data.ncfreelist;
+        cm_data.ncfreelist = &cm_data.nameCache[i];
     }
     lock_ReleaseWrite(&cm_dnlcLock);
    
@@ -519,40 +524,41 @@ cm_dnlcPurgeVol( fidp )
 long
 cm_dnlcValidate(void)
 {
-    int i;
+    int i, purged = 0;
     cm_nc_t * ncp;
-    
+
+  retry:
     // are all nameCache entries marked with the magic bit?
     for (i=0; i<NCSIZE; i++)
     {
         if (cm_data.nameCache[i].magic != CM_DNLC_MAGIC) {
             afsi_log("cm_dnlcValidate failure: cm_data.nameCache[%d].magic != CM_DNLC_MAGIC", i);
             fprintf(stderr, "cm_dnlcValidate failure: cm_data.nameCache[%d].magic != CM_DNLC_MAGIC\n", i);
-            return -1;
+            goto purge;
         }
         if (cm_data.nameCache[i].next &&
             cm_data.nameCache[i].next->magic != CM_DNLC_MAGIC) {
             afsi_log("cm_dnlcValidate failure: cm_data.nameCache[%d].next->magic != CM_DNLC_MAGIC", i);
             fprintf(stderr, "cm_dnlcValidate failure: cm_data.nameCache[%d].next->magic != CM_DNLC_MAGIC\n", i);
-            return -2;
+            goto purge;
         }
         if (cm_data.nameCache[i].prev &&
             cm_data.nameCache[i].prev->magic != CM_DNLC_MAGIC) {
             afsi_log("cm_dnlcValidate failure: cm_data.nameCache[%d].prev->magic != CM_DNLC_MAGIC", i);
             fprintf(stderr, "cm_dnlcValidate failure: cm_data.nameCache[%d].prev->magic != CM_DNLC_MAGIC\n", i);
-            return -3;
+            goto purge;
         }
         if (cm_data.nameCache[i].dirp &&
             cm_data.nameCache[i].dirp->magic != CM_SCACHE_MAGIC) {
             afsi_log("cm_dnlcValidate failure: cm_data.nameCache[%d].dirp->magic != CM_SCACHE_MAGIC", i);
             fprintf(stderr, "cm_dnlcValidate failure: cm_data.nameCache[%d].dirp->magic != CM_SCACHE_MAGIC\n", i);
-            return -4;
+            goto purge;
         }
         if (cm_data.nameCache[i].vp &&
             cm_data.nameCache[i].vp->magic != CM_SCACHE_MAGIC) {
             afsi_log("cm_dnlcValidate failure: cm_data.nameCache[%d].vp->magic != CM_SCACHE_MAGIC", i);
             fprintf(stderr, "cm_dnlcValidate failure: cm_data.nameCache[%d].vp->magic != CM_SCACHE_MAGIC\n", i);
-            return -5;
+            goto purge;
         }
     }
 
@@ -563,54 +569,82 @@ cm_dnlcValidate(void)
             if (ncp->magic != CM_DNLC_MAGIC) {
                 afsi_log("cm_dnlcValidate failure: ncp->magic != CM_DNLC_MAGIC");
                 fprintf(stderr, "cm_dnlcValidate failure: ncp->magic != CM_DNLC_MAGIC\n");
-                return -6;
+                goto purge;
             }
             if (ncp->prev && ncp->prev->magic != CM_DNLC_MAGIC) {
                 afsi_log("cm_dnlcValidate failure: ncp->prev->magic != CM_DNLC_MAGIC");
                 fprintf(stderr, "cm_dnlcValidate failure: ncp->prev->magic != CM_DNLC_MAGIC\n");
-                return -7;
+                goto purge;
             }
             if (ncp->dirp && ncp->dirp->magic != CM_SCACHE_MAGIC) {
                 afsi_log("cm_dnlcValidate failure: ncp->dirp->magic != CM_DNLC_MAGIC");
                 fprintf(stderr, "cm_dnlcValidate failure: ncp->dirp->magic != CM_DNLC_MAGIC\n");
-                return -8;
+                goto purge;
             }
             if (ncp->vp && ncp->vp->magic != CM_SCACHE_MAGIC) {
                 afsi_log("cm_dnlcValidate failure: ncp->vp->magic != CM_DNLC_MAGIC");
                 fprintf(stderr, "cm_dnlcValidate failure: ncp->vp->magic != CM_DNLC_MAGIC\n");
-                return -9;
+                goto purge;
             }
         }
     }
 
     // is the freelist stable?
     if ( cm_data.ncfreelist ) {
-        for (ncp = cm_data.ncfreelist; ncp; 
-             ncp = ncp->next != cm_data.ncfreelist ? ncp->next : NULL) {
+        for (ncp = cm_data.ncfreelist, i = 0; ncp && i < NCSIZE; 
+             ncp = ncp->next != cm_data.ncfreelist ? ncp->next : NULL, i++) {
             if (ncp->magic != CM_DNLC_MAGIC) {
                 afsi_log("cm_dnlcValidate failure: ncp->magic != CM_DNLC_MAGIC");
                 fprintf(stderr, "cm_dnlcValidate failure: ncp->magic != CM_DNLC_MAGIC\n");
-                return -10;
+                goto purge;
             }
-            if (ncp->prev && ncp->prev->magic != CM_DNLC_MAGIC) {
-                afsi_log("cm_dnlcValidate failure: ncp->prev->magic != CM_DNLC_MAGIC");
-                fprintf(stderr, "cm_dnlcValidate failure: ncp->prev->magic != CM_DNLC_MAGIC\n");
-                return -11;
+            if (ncp->prev) {
+                afsi_log("cm_dnlcValidate failure: ncp->prev != NULL");
+                fprintf(stderr, "cm_dnlcValidate failure: ncp->prev != NULL\n");
+                goto purge;
             }
-            if (ncp->dirp && ncp->dirp->magic != CM_SCACHE_MAGIC) {
-                afsi_log("cm_dnlcValidate failure: ncp->dirp->magic != CM_DNLC_MAGIC");
-                fprintf(stderr, "cm_dnlcValidate failure: ncp->dirp->magic != CM_DNLC_MAGIC\n");
-               return -12;
+            if (ncp->key) {
+                afsi_log("cm_dnlcValidate failure: ncp->key != 0");
+                fprintf(stderr, "cm_dnlcValidate failure: ncp->key != 0\n");
+                goto purge;
             }
-            if (ncp->vp && ncp->vp->magic != CM_SCACHE_MAGIC) {
-                afsi_log("cm_dnlcValidate failure: ncp->vp->magic != CM_DNLC_MAGIC");
-                fprintf(stderr, "cm_dnlcValidate failure: ncp->vp->magic != CM_DNLC_MAGIC\n");
-                return -13;
+            if (ncp->dirp) {
+                afsi_log("cm_dnlcValidate failure: ncp->dirp != NULL");
+                fprintf(stderr, "cm_dnlcValidate failure: ncp->dirp != NULL\n");
+               goto purge;
+            }
+            if (ncp->vp) {
+                afsi_log("cm_dnlcValidate failure: ncp->vp != NULL");
+                fprintf(stderr, "cm_dnlcValidate failure: ncp->vp != NULL\n");
+                goto purge;
             }
         }
-    }
 
+        if ( i == NCSIZE && ncp ) {
+            afsi_log("cm_dnlcValidate failure: dnlc freeList corrupted");
+            fprintf(stderr, "cm_dnlcValidate failure: dnlc freeList corrupted\n");
+            goto purge;
+        }
+    }
     return 0;
+
+  purge:
+    if ( purged )
+        return -1;
+
+    afsi_log("cm_dnlcValidate information: purging");
+    fprintf(stderr, "cm_dnlcValidate information: purging\n");
+    cm_data.ncfreelist = (cm_nc_t *) 0;
+    memset (cm_data.nameCache, 0, sizeof(cm_nc_t) * NCSIZE);
+    memset (cm_data.nameHash, 0, sizeof(cm_nc_t *) * NHSIZE);
+    for (i=0; i<NCSIZE; i++)
+    {
+        cm_data.nameCache[i].magic = CM_DNLC_MAGIC;
+        cm_data.nameCache[i].next = cm_data.ncfreelist;
+        cm_data.ncfreelist = &cm_data.nameCache[i];
+    }
+    purged = 1;
+    goto retry;
 }
 
 void 

diff --git a/src/WINNT/afsd/cm_memmap.c b/src/WINNT/afsd/cm_memmap.c
index 8f63d7e..50ae0b4 100644 (file)
--- a/src/WINNT/afsd/cm_memmap.c
+++ b/src/WINNT/afsd/cm_memmap.c
@@ -400,13 +400,11 @@ cm_ValidateMappedMemory(char * cachePath)
     if (!cm_IsCacheValid()) {
         fprintf(stderr,"Cache file fails validation test\n");
         UnmapViewOfFile(config_data_p);
-        CloseHandle(hm);
         return CM_ERROR_INVAL;
     }
 
     fprintf(stderr,"Cache passes validation test\n");
     UnmapViewOfFile(config_data_p);
-    CloseHandle(hm);
     return 0;
 }