HAMMER UTILITY - Fix seg-fault on corrupt blockmap during recovery

* Fix a seg-fault which occurs when the recover directive hits a bad
  blockmap entry.

Reported-by: "Miro Svetlik" <miro@svetlik.be>

diff --git a/sbin/hammer/blockmap.c b/sbin/hammer/blockmap.c
index d61bfa5..82ad0b5 100644 (file)
--- a/sbin/hammer/blockmap.c
+++ b/sbin/hammer/blockmap.c
@@ -55,6 +55,11 @@ blockmap_lookup(hammer_off_t zone_offset,
        int i;
        int error = 0;
 
+       if (save_layer1)
+               *save_layer1 = NULL;
+       if (save_layer2)
+               *save_layer2 = NULL;
+
        zone = HAMMER_ZONE_DECODE(zone_offset);
 
        if (AssertOnFailure) {
@@ -101,6 +106,9 @@ blockmap_lookup(hammer_off_t zone_offset,
        /*
         * The blockmap should match the requested zone (else the volume
         * header is mashed).
+        *
+        * Note that a valid offset can still be returned if AssertOnFailure
+        * is zero.
         */
        if (AssertOnFailure) {
                assert(HAMMER_ZONE_DECODE(blockmap->alloc_offset) == zone);
@@ -124,8 +132,13 @@ blockmap_lookup(hammer_off_t zone_offset,
                        HAMMER_BLOCKMAP_LAYER1_OFFSET(result_offset);
        layer1 = get_buffer_data(layer1_offset, &buffer, 0);
        if (AssertOnFailure) {
+               assert(layer1);
                assert(layer1->phys_offset != HAMMER_BLOCKMAP_UNAVAIL);
        } else {
+               if (layer1 == NULL) {
+                       error = EDOM;
+                       goto done;
+               }
                if (layer1->phys_offset == HAMMER_BLOCKMAP_UNAVAIL) {
                        error = EDOM;
                        goto done;
@@ -140,15 +153,22 @@ blockmap_lookup(hammer_off_t zone_offset,
        layer2_offset = layer1->phys_offset +
                        HAMMER_BLOCKMAP_LAYER2_OFFSET(result_offset);
        layer2 = get_buffer_data(layer2_offset, &buffer, 0);
-       if (save_layer2)
-               *save_layer2 = *layer2;
 
        if (AssertOnFailure) {
+               assert(layer2);
                assert(layer2->zone == zone);
        } else {
-               if (layer2->zone != zone)
+               if (layer2 == NULL) {
                        error = EDOM;
+                       goto done;
+               }
+               if (layer2->zone != zone) {
+                       error = EDOM;
+                       goto done;
+               }
        }
+       if (save_layer2)
+               *save_layer2 = *layer2;
 
 done:
        if (buffer)