[PATCH] ls: fix crash printing SELinux context for unstatable files

[Pádraig Brady]

This crash was identified by Cyber Independent Testing Lab:
https://cyber-itl.org/2020/10/28/citl-7000-defects.html
and was introduced with commit v6.9.90-11-g4245876e2

* src/ls.c (gobble_file): Ensure scontext is initialized
in the case where files are not statable.
* tests/ls/selinux-segfault.sh: Renamed from proc-selinux-segfault.sh,
and added test case for broken symlinks.
* tests/local.mk: Adjust for the renamed test.
* NEWS: Mention the bug fix.
---
 NEWS                                                   |  3 +++
 src/ls.c                                               |  3 +++
 tests/local.mk                                         |  2 +-
 .../{proc-selinux-segfault.sh => selinux-segfault.sh}  | 10 ++++++++--
 4 files changed, 15 insertions(+), 3 deletions(-)
 rename tests/ls/{proc-selinux-segfault.sh => selinux-segfault.sh} (77%)

diff --git a/NEWS b/NEWS
index 392d0ce1e..657477ac7 100644
--- a/NEWS
+++ b/NEWS
@@ -17,6 +17,9 @@ GNU coreutils NEWS                                    -*- 
outline -*-
   heavily changed during the run.
   [bug introduced in coreutils-8.25]
 
+  ls no longer crashes when printing the SELinux context for unstatable files.
+  [bug introduced in coreutils-6.9.91]
+
 ** Changes in behavior
 
   cp and install now default to copy-on-write (COW) if available.
diff --git a/src/ls.c b/src/ls.c
index 1f6afbc0e..1b4834cec 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -3424,6 +3424,9 @@ gobble_file (char const *name, enum filetype type, ino_t 
inode,
              provokes an exit status of 1.  */
           file_failure (command_line_arg,
                         _("cannot access %s"), full_name);
+
+          f->scontext = UNKNOWN_SECURITY_CONTEXT;
+
           if (command_line_arg)
             return 0;
 
diff --git a/tests/local.mk b/tests/local.mk
index 799200393..e1c4675c2 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -613,7 +613,7 @@ all_tests =                                 \
   tests/ls/multihardlink.sh                    \
   tests/ls/no-arg.sh                           \
   tests/ls/no-cap.sh                           \
-  tests/ls/proc-selinux-segfault.sh            \
+  tests/ls/selinux-segfault.sh                 \
   tests/ls/quote-align.sh                      \
   tests/ls/readdir-mountpoint-inode.sh         \
   tests/ls/recursive.sh                                \
diff --git a/tests/ls/proc-selinux-segfault.sh b/tests/ls/selinux-segfault.sh
similarity index 77%
rename from tests/ls/proc-selinux-segfault.sh
rename to tests/ls/selinux-segfault.sh
index 831a00e17..e2b7ef638 100755
--- a/tests/ls/proc-selinux-segfault.sh
+++ b/tests/ls/selinux-segfault.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
-# ls -l /proc/sys would segfault when built against libselinux1 2.0.15-2+b1
+# Ensure we don't segfault in selinux handling
 
 # Copyright (C) 2008-2020 Free Software Foundation, Inc.
 
@@ -19,9 +19,15 @@
 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
 print_ver_ ls
 
+# ls -l /proc/sys would segfault when built against libselinux1 2.0.15-2+b1
 f=/proc/sys
 test -r $f || f=.
-
 ls -l $f > out || fail=1
 
+# ls <= 8.32 would segfault when printing
+# the security context of broken symlink targets
+mkdir sedir || framework_failure_
+ln -sf missing sedir/broken || framework_failure_
+returns_ 1 ls -L -R -Z -m sedir > out || fail=1
+
 Exit $fail
-- 
2.26.2