[PATCH 2/2] overlay: regression test for two file handle bugs

[Amir Goldstein <amir73il@gmail.com>]

Test two overlayfs file handle bugs:

 1. Failure to query file handle size
    Fixed by kernel commit:
        ovl: return required buffer size for file handles

 2. Kernel OOPS on open by hand crafted malformed file handle
    Fixed by kernel commit:
        ovl: potential crash in ovl_fid_to_fh()

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 tests/overlay/073     | 80 +++++++++++++++++++++++++++++++++++++++++++
 tests/overlay/073.out |  2 ++
 tests/overlay/group   |  1 +
 3 files changed, 83 insertions(+)
 create mode 100755 tests/overlay/073
 create mode 100644 tests/overlay/073.out

diff --git a/tests/overlay/073 b/tests/overlay/073
new file mode 100755
index 00000000..72233fae
--- /dev/null
+++ b/tests/overlay/073
@@ -0,0 +1,80 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2020 CTERA Networks. All Rights Reserved.
+#
+# FS QA Test No. 073
+#
+# Test two overlayfs file handle bugs:
+# 1. Failure to query file handle size
+#    Fixed by kernel commit:
+#        ovl: return required buffer size for file handles
+#
+# 2. Kernel OOPS on open by hand crafted malformed file handle
+#    Fixed by kernel commit:
+#        ovl: potential crash in ovl_fid_to_fh()
+#
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	#rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+
+_supported_fs overlay
+_supported_os Linux
+_require_scratch
+_require_test_program "open_by_handle"
+# We need to require all features together, because nfs_export cannot
+# be enabled when index is disabled
+_require_scratch_overlay_features index nfs_export
+
+rm -f $seqres.full
+
+_scratch_mkfs
+_scratch_mount -o "index=on,nfs_export=on"
+
+testdir=$SCRATCH_MNT/testdir
+
+# Create directory with test file
+$here/src/open_by_handle -cp $testdir
+
+# Test query file handle size on dir and file
+$here/src/open_by_handle -pz $testdir
+
+# Export file handle into tmp file
+$here/src/open_by_handle -o $tmp.file_handle $testdir
+
+# Verify open by exported file handle
+$here/src/open_by_handle -i $tmp.file_handle $testdir
+
+# Mangle the exported file handle:
+# handle_bytes = 1
+# handle_type = OVL_FILEID_V0 (0xfb)
+# File handle is encoded in host order
+# The command below crafts this header for little endian.
+# On different big endian architectures the file handle will still
+# be malformed just not with the specific values to trigger the bug
+$XFS_IO_PROG -c "pwrite -S 0 0 8" -c "pwrite -S 1 0 1" -c "pwrite -S 0xfb 4 1" $tmp.file_handle >> $seqres.full
+
+# Verify failure to open by mangled file handle
+# This will trigger NULL pointer dereference on affected kernels
+$here/src/open_by_handle -i $tmp.file_handle $testdir 2>> $seqres.full && \
+	_fail "open by mangaled file handle is expected to fail"
+
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/overlay/073.out b/tests/overlay/073.out
new file mode 100644
index 00000000..d107704c
--- /dev/null
+++ b/tests/overlay/073.out
@@ -0,0 +1,2 @@
+QA output created by 073
+Silence is golden
diff --git a/tests/overlay/group b/tests/overlay/group
index 82876d09..5625a46d 100644
--- a/tests/overlay/group
+++ b/tests/overlay/group
@@ -75,3 +75,4 @@
 070 auto quick copyup redirect nested
 071 auto quick copyup redirect nested nonsamefs
 072 auto quick copyup hardlink
+073 auto quick exportfs dangerous
-- 
2.17.1