[lldb-dev] [Bug 26842] New: LLDB GUI segfault when continuing with the thread frame list expanded
lldb-dev at lists.llvm.org
Fri Mar 4 09:49:27 PST 2016
Bug ID: 26842
Summary: LLDB GUI segfault when continuing with the thread
frame list expanded
OS: MacOS X
Component: All Bugs
Assignee: lldb-dev at lists.llvm.org
Reporter: kknb1056 at gmail.com
CC: llvm-bugs at lists.llvm.org
Created attachment 15986
Example backtrace of a crash, plus the proposed patch to fix
I have a fix for this, but I wasn't sure if the correct etiquette is to file a
bug report before posting a patch to lldb-commits?
If the frame stack changes while the list is expanded in the Threads window,
there will be a high likelihood of a segfault. For example, expanding the list
and then "continue" to another breakpoint where the list is different. I can
give a specific program and instructions if required but any program should do
it. An example stack trace is attached.
This is with the version of lldb shipped with XCode 7.2.1 (lldb-3188.8.131.52) as
well as the current head (as at 04/Mar/16).
The problem is that, when creating the updated list it is done with
vector<TreeItem>::resize( <new size>, <new value> );
(via calls to TreeItem::Resize in IOHandler.cpp lines 3312 and 3422). The
intention of the code is to fill the m_children vector with copies of <new
value>, but std::vector::resize only uses the <new value> for new values -
items already in the vector are left untouched. Hence all items up to the old
size will have invalid pointers to parent etcetera, and subsequent Draw calls
will screw up.
I propose to insert a call to TreeItem::ClearChildren() immediately before the
TreeItem::Resize(..) calls so that all children correctly take on the new
A patch is attached, but I could only append one file so it's after the
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