From 48e7ab89a56998ed63f24549d4fc7fc1289ad508 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt@redhat.com>
Date: Thu, 21 Sep 2017 10:22:38 +0100
Subject: [PATCH] [*_dump] Fix segfault when given a tiny metadata file

---
 caching/metadata.cc                         | 6 +++++-
 era/metadata.cc                             | 6 +++++-
 functional-tests/cache-functional-tests.scm | 5 +++++
 functional-tests/era-functional-tests.scm   | 8 ++++++++
 functional-tests/thin-functional-tests.scm  | 9 +++++++++
 thin-provisioning/metadata.cc               | 6 +++++-
 6 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/caching/metadata.cc b/caching/metadata.cc
index 7d8bfae..91806f4 100644
--- a/caching/metadata.cc
+++ b/caching/metadata.cc
@@ -13,7 +13,11 @@ namespace {
 	// FIXME: duplication
 	transaction_manager::ptr
 	open_tm(block_manager<>::ptr bm) {
-		space_map::ptr sm(new core_map(bm->get_nr_blocks()));
+		auto nr_blocks = bm->get_nr_blocks();
+		if (!nr_blocks)
+			throw runtime_error("Metadata is not large enough for superblock.");
+
+		space_map::ptr sm(new core_map(nr_blocks));
 		sm->inc(SUPERBLOCK_LOCATION);
 		transaction_manager::ptr tm(new transaction_manager(bm, sm));
 		return tm;
diff --git a/era/metadata.cc b/era/metadata.cc
index dd4fe7a..40861b1 100644
--- a/era/metadata.cc
+++ b/era/metadata.cc
@@ -11,7 +11,11 @@ namespace {
 	// FIXME: duplication
 	transaction_manager::ptr
 	open_tm(block_manager<>::ptr bm) {
-		space_map::ptr sm(new core_map(bm->get_nr_blocks()));
+		auto nr_blocks = bm->get_nr_blocks();
+		if (!nr_blocks)
+			throw runtime_error("Metadata is not large enough for superblock.");
+
+		space_map::ptr sm(new core_map(nr_blocks));
 		sm->inc(SUPERBLOCK_LOCATION);
 		transaction_manager::ptr tm(new transaction_manager(bm, sm));
 		return tm;
diff --git a/functional-tests/cache-functional-tests.scm b/functional-tests/cache-functional-tests.scm
index eabca3d..4084c11 100644
--- a/functional-tests/cache-functional-tests.scm
+++ b/functional-tests/cache-functional-tests.scm
@@ -245,6 +245,11 @@
     (receive (stdout stderr) (run-fail "cache_dump")
       (assert-starts-with "No input file provided." stderr)))
 
+  (define-scenario (cache-dump small-input-file)
+    "Fails with small input file"
+    (with-temp-file-sized ((md "cache.bin" 512))
+      (run-fail "cache_dump" md)))
+
   (define-scenario (cache-dump restore-is-noop)
     "cache_dump followed by cache_restore is a noop."
     (with-valid-metadata (md)
diff --git a/functional-tests/era-functional-tests.scm b/functional-tests/era-functional-tests.scm
index d381cea..bf124ad 100644
--- a/functional-tests/era-functional-tests.scm
+++ b/functional-tests/era-functional-tests.scm
@@ -180,6 +180,14 @@
           (assert-eof stdout)
           (assert-starts-with "Couldn't stat file" stderr)))))
 
+  ;;;-----------------------------------------------------------
+  ;;; era_dump scenarios
+  ;;;-----------------------------------------------------------
+  (define-scenario (era-dump small-input-file)
+    "Fails with small input file"
+    (with-temp-file-sized ((md "era.bin" 512))
+      (run-fail "era_dump" md)))
+
   (define-scenario (era-dump restore-is-noop)
     "era_dump followed by era_restore is a noop."
     (with-valid-metadata (md)
diff --git a/functional-tests/thin-functional-tests.scm b/functional-tests/thin-functional-tests.scm
index a2991d6..eb96d51 100644
--- a/functional-tests/thin-functional-tests.scm
+++ b/functional-tests/thin-functional-tests.scm
@@ -187,6 +187,15 @@
         (receive (stdout _) (thin-restore "-i" xml "-o" md "--quiet")
           (assert-eof stdout)))))
 
+  ;;;-----------------------------------------------------------
+  ;;; thin_dump scenarios
+  ;;;-----------------------------------------------------------
+
+  (define-scenario (thin-dump small-input-file)
+    "Fails with small input file"
+    (with-temp-file-sized ((md "thin.bin" 512))
+      (run-fail "thin_dump" md)))
+
   (define-scenario (thin-dump restore-is-noop)
     "thin_dump followed by thin_restore is a noop."
     (with-valid-metadata (md)
diff --git a/thin-provisioning/metadata.cc b/thin-provisioning/metadata.cc
index 77e0428..ac8b63e 100644
--- a/thin-provisioning/metadata.cc
+++ b/thin-provisioning/metadata.cc
@@ -42,7 +42,11 @@ namespace {
 
 	transaction_manager::ptr
 	open_tm(block_manager<>::ptr bm) {
-		space_map::ptr sm(new core_map(bm->get_nr_blocks()));
+		auto nr_blocks = bm->get_nr_blocks();
+		if (!nr_blocks)
+			throw runtime_error("Metadata is not large enough for superblock.");
+
+		space_map::ptr sm(new core_map(nr_blocks));
 		sm->inc(SUPERBLOCK_LOCATION);
 		transaction_manager::ptr tm(new transaction_manager(bm, sm));
 		return tm;