From 38c2059aec111174bcdc06c8006d998c513c8b8c Mon Sep 17 00:00:00 2001 From: Pavel Labath Date: Fri, 5 May 2017 11:51:21 +0000 Subject: Fix segfault resulting from empty print prompt Summary: I have found a way to segfault lldb in 7 keystrokes! Steps to reproduce: 1) Launch lldb 2) Type `print` and hit enter. lldb will now prompt you to type a list of expressions, followed by an empty line. 3) Hit enter, indicating the end of your input. 4) Segfault! After some investigation, I've found the issue in Host/common/Editline.cpp. Editline::MoveCursor() relies on m_input_lines not being empty when the `to` argument is CursorPosition::BlockEnd. This scenario, as far as I can tell, occurs in one specific instance: In Editline::EndOrAddLineCommand() when the list of lines being processed contains exactly one string (""). Meeting this condition is fairly simple, I have posted steps to reproduce above. Reviewers: krytarowski, zturner, labath Reviewed By: labath Subscribers: scott.smith, lldb-commits Differential Revision: https://reviews.llvm.org/D32421 Patch by Alex Langford. llvm-svn: 302225 --- .../multiline/TestMultilineExpressions.py | 28 ++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'lldb/packages/Python/lldbsuite/test/expression_command') diff --git a/lldb/packages/Python/lldbsuite/test/expression_command/multiline/TestMultilineExpressions.py b/lldb/packages/Python/lldbsuite/test/expression_command/multiline/TestMultilineExpressions.py index b1b5cbe677c..aa369ebeff8 100644 --- a/lldb/packages/Python/lldbsuite/test/expression_command/multiline/TestMultilineExpressions.py +++ b/lldb/packages/Python/lldbsuite/test/expression_command/multiline/TestMultilineExpressions.py @@ -12,6 +12,7 @@ from lldbsuite.test import lldbutil class MultilineExpressionsTestCase(TestBase): mydir = TestBase.compute_mydir(__file__) + NO_DEBUG_INFO_TESTCASE = True def setUp(self): # Call super's setUp(). @@ -60,3 +61,30 @@ class MultilineExpressionsTestCase(TestBase): child.expect_exact(prompt) self.expect(child.before, exe=False, patterns=['= 5']) + + @skipIfRemote + @expectedFailureAll( + oslist=["windows"], + bugnumber="llvm.org/pr22274: need a pexpect replacement for windows") + def test_empty_list(self): + """Test printing an empty list of expressions""" + import pexpect + prompt = "(lldb) " + + # So that the child gets torn down after the test + self.child = pexpect.spawn( + "%s %s" % + (lldbtest_config.lldbExec, self.lldbOption)) + child = self.child + + # Turn on logging for what the child sends back. + if self.TraceOn(): + child.logfile_read = sys.stdout + + # We expect a prompt, then send "print" to start a list of expressions, + # then an empty line. We expect a prompt back. + child.expect_exact(prompt) + child.sendline("print") + child.expect_exact('1:') + child.sendline("") + child.expect_exact(prompt) -- cgit v1.2.3