MDEV-8799: Server crashes in btr_defragment_add_index, encryption.innodb-bad-key-change5 and alike fail in buildbot

Problem was unsafe access to NULL pointer. Added additional checks to avoid access to NULL pointer.

Author: janlindstrom

storage/innobase/btr/btr0cur.cc

@@ -1671,15 +1671,24 @@ btr_cur_pessimistic_insert(
 btr_cur_get_page_zip(cursor),
 thr_get_trx(thr)->id, mtr);
 }
-if (!page_rec_is_infimum(btr_cur_get_rec(cursor))
- || btr_page_get_prev(
-buf_block_get_frame(
-btr_cur_get_block(cursor)), mtr)
- == FIL_NULL) {
+
+if (!page_rec_is_infimum(btr_cur_get_rec(cursor))) {
 /* split and inserted need to call
 lock_update_insert() always. */
 inherit = TRUE;
 }
+
+buf_block_t* block = btr_cur_get_block(cursor);
+buf_frame_t* frame = NULL;
+
+if (block) {
+frame = buf_block_get_frame(block);
+}
+/* split and inserted need to call
+lock_update_insert() always. */
+if (frame && btr_page_get_prev(frame, mtr) == FIL_NULL) {
+inherit = TRUE;
+}
 }
 
 #ifdef BTR_CUR_ADAPT

storage/innobase/btr/btr0defragment.cc

@@ -220,8 +220,12 @@ btr_defragment_add_index(
 
 mtr_start(&mtr);
 // Load index rood page.
-page_t* page = btr_page_get(space, zip_size, page_no,
- RW_NO_LATCH, index, &mtr);
+buf_block_t* block = btr_block_get(space, zip_size, page_no, RW_NO_LATCH, index, &mtr);
+page_t* page = NULL;
+
+if (block) {
+page = buf_block_get_frame(block);
+}
 
 if (page == NULL && index->table->is_encrypted) {
 mtr_commit(&mtr);

storage/innobase/btr/btr0scrub.cc

@@ -750,9 +750,13 @@ btr_scrub_page(
 mtr_t* mtr) /*!< in: mtr */
 {
 /* recheck if page needs scrubbing (knowing allocation status) */
-int needs_scrubbing = btr_page_needs_scrubbing(
-scrub_data, block, allocated);
-if (needs_scrubbing != BTR_SCRUB_PAGE) {
+int needs_scrubbing = BTR_SCRUB_SKIP_PAGE_AND_CLOSE_TABLE;
+
+if (block) {
+btr_page_needs_scrubbing(scrub_data, block, allocated);
+}
+
+if (!block || needs_scrubbing != BTR_SCRUB_PAGE) {
 mtr_commit(mtr);
 return needs_scrubbing;
 }
@@ -784,7 +788,12 @@ btr_scrub_page(
 return BTR_SCRUB_SKIP_PAGE_AND_CLOSE_TABLE;
 }
 
-if (btr_page_get_index_id(buf_block_get_frame(block)) !=
+buf_frame_t* frame = NULL;
+
+if (block) {
+frame = buf_block_get_frame(block);
+}
+if (!frame || btr_page_get_index_id(frame) !=
  scrub_data->current_index->id) {
 /* page has been reallocated to new index */
 mtr_commit(mtr);

storage/xtradb/btr/btr0cur.cc

@@ -1795,15 +1795,24 @@ btr_cur_pessimistic_insert(
 btr_cur_get_page_zip(cursor),
 thr_get_trx(thr)->id, mtr);
 }
-if (!page_rec_is_infimum(btr_cur_get_rec(cursor))
- || btr_page_get_prev(
-buf_block_get_frame(
-btr_cur_get_block(cursor)), mtr)
- == FIL_NULL) {
+
+if (!page_rec_is_infimum(btr_cur_get_rec(cursor))) {
 /* split and inserted need to call
 lock_update_insert() always. */
 inherit = TRUE;
 }
+
+buf_block_t* block = btr_cur_get_block(cursor);
+buf_frame_t* frame = NULL;
+
+if (block) {
+frame = buf_block_get_frame(block);
+}
+/* split and inserted need to call
+lock_update_insert() always. */
+if (frame && btr_page_get_prev(frame, mtr) == FIL_NULL) {
+inherit = TRUE;
+}
 }
 
 #ifdef BTR_CUR_ADAPT

storage/xtradb/btr/btr0defragment.cc

@@ -220,8 +220,12 @@ btr_defragment_add_index(
 
 mtr_start(&mtr);
 // Load index rood page.
-page_t* page = btr_page_get(space, zip_size, page_no,
- RW_NO_LATCH, index, &mtr);
+buf_block_t* block = btr_block_get(space, zip_size, page_no, RW_NO_LATCH, index, &mtr);
+page_t* page = NULL;
+
+if (block) {
+page = buf_block_get_frame(block);
+}
 
 if (page == NULL && index->table->is_encrypted) {
 mtr_commit(&mtr);

storage/xtradb/btr/btr0scrub.cc

@@ -750,9 +750,13 @@ btr_scrub_page(
 mtr_t* mtr) /*!< in: mtr */
 {
 /* recheck if page needs scrubbing (knowing allocation status) */
-int needs_scrubbing = btr_page_needs_scrubbing(
-scrub_data, block, allocated);
-if (needs_scrubbing != BTR_SCRUB_PAGE) {
+int needs_scrubbing = BTR_SCRUB_SKIP_PAGE_AND_CLOSE_TABLE;
+
+if (block) {
+btr_page_needs_scrubbing(scrub_data, block, allocated);
+}
+
+if (!block || needs_scrubbing != BTR_SCRUB_PAGE) {
 mtr_commit(mtr);
 return needs_scrubbing;
 }
@@ -784,7 +788,12 @@ btr_scrub_page(
 return BTR_SCRUB_SKIP_PAGE_AND_CLOSE_TABLE;
 }
 
-if (btr_page_get_index_id(buf_block_get_frame(block)) !=
+buf_frame_t* frame = NULL;
+
+if (block) {
+frame = buf_block_get_frame(block);
+}
+if (!frame || btr_page_get_index_id(frame) !=
  scrub_data->current_index->id) {
 /* page has been reallocated to new index */
 mtr_commit(mtr);