[BUG] LLDB crash with a simple help commond

[zte-majiang]

Description

/mnt/d/opensource/android_ndk/android-ndk-r23$ ./toolchains/llvm/prebuilt/linux-x86_64/bin/lldb.sh
Cannot read termcap database;
using dumb terminal settings.
(lldb) help x
PLEASE submit a bug report to https://github.com/android-ndk/ndk/issues and include the crash backtrace.
Stack dump:
0. Program arguments: /mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/lldb
#0 0x0000000000231665 (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/lldb+0x231665)
#1 0x0000000000231bb0 (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/lldb+0x231bb0)
#2 0x0000000000231b1a (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/lldb+0x231b1a)
#3 0x00007f5ea9c003c0 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x153c0)
#4 0x00007f5ea9012395 lldb_private::Options::GenerateOptionUsage(lldb_private::Stream&, lldb_private::CommandObject*, unsigned int) (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x442e395)
#5 0x00007f5ea8ffd6e1 lldb_private::CommandObject::GenerateHelpText(lldb_private::Stream&) (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x44196e1)
#6 0x00007f5ea94cd5cb lldb_private::CommandObjectHelp::DoExecute(lldb_private::Args&, lldb_private::CommandReturnObject&) (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x48e95cb)
#7 0x00007f5ea8ffe38f lldb_private::CommandObjectParsed::Execute(char const*, lldb_private::CommandReturnObject&) (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x441a38f)
#8 0x00007f5ea8ff18ac lldb_private::CommandInterpreter::HandleCommand(char const*, lldb_private::LazyBool, lldb_private::CommandReturnObject&, lldb_private::ExecutionContext*, bool, bool) (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x440d8ac)
#9 0x00007f5ea8ff6240 lldb_private::CommandInterpreter::IOHandlerInputComplete(lldb_private::IOHandler&, std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator >&) (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x4412240)
#10 0x00007f5ea8f4f346 lldb_private::IOHandlerEditline::Run() (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x436b346)
#11 0x00007f5ea8f325ed lldb_private::Debugger::RunIOHandlers() (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x434e5ed)
#12 0x00007f5ea8ff78bc lldb_private::CommandInterpreter::RunCommandInterpreter(lldb_private::CommandInterpreterRunOptions&) (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x44138bc)
#13 0x00007f5ea8a9db8d lldb::SBDebugger::RunCommandInterpreter(bool, bool) (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/../lib64/liblldb.so.12git+0x3eb9b8d)
#14 0x00000000002388b1 main (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/lldb+0x2388b1)
#15 0x00007f5ea47570b3 __libc_start_main /build/glibc-eX1tMB/glibc-2.31/csu/../csu/libc-start.c:342:3
#16 0x0000000000231d95 _start (/mnt/d/opensource/android_ndk/android-ndk-r23/toolchains/llvm/prebuilt/linux-x86_64/bin/lldb+0x231d95)
./toolchains/llvm/prebuilt/linux-x86_64/bin/lldb.sh: line 5: 3618 Segmentation fault (core dumped) "$CURDIR/lldb" "$@"

Environment Details

Windows10 WSL Ubuntu20.04

:/mnt/d/opensource/android_ndk/android-ndk-r23$ uname -a
Linux P80299346 4.4.0-17763-Microsoft #1432-Microsoft Mon Aug 18 18:18:00 PST 2020 x86_64 x86_64 x86_64 GNU/Linux
:/mnt/d/opensource/android_ndk/android-ndk-r23$ cat source.properties
Pkg.Desc = Android NDK
Pkg.Revision = 23.0.7599858

[DanAlbert]

Repros on debian as well, so it's at least not a WSL issue. It looks like it is specifically a crash that happens when you run help with an unrecognized argument (help is fine, help list is fine, help x is not). Still present in the r24 canary.

[rprichard]

It looks like it is specifically a crash that happens when you run help with an unrecognized argument

help asdfasdfasdf prints error: 'asdfasdfasdf' is not a known command. The x command is supposed to be short for memory read, and help memory read also segfaults. They don't segfault in the upstream clang+llvm-12.0.0-x86_64-linux-gnu-ubuntu-20.04 binary.

It looks broken in r416183{b,c,c1} and fixed in r428724 and r433403.

[DanAlbert]

Thanks for checking that. Nothing for us to do then other than update to the newer build, unless we think this is worth cherry-picking to r23c?

[pirama-arumuga-nainar]

FWIW, it was easy to find the fix by looking for memory read in git log lldb: https://reviews.llvm.org/D94917 (9a7672ac4980bca8829814e1e49e1c201a5bf9b6).

I don't think we should respin toolchain specifically for this issue though.

[DanAlbert]

I don't think we should respin toolchain specifically for this issue though.

Agreed. We should pick it up if (and realistically, when) we need to respin the toolchain for other issues. Triaged to r23c but will punt to r23d if we somehow manage to make it through a minor release without otherwise updating the toolchain.

[DanAlbert]

Confirmed fixed with https://android-review.googlesource.com/c/platform/ndk/+/1839724.

[stephenhines]

https://android-review.googlesource.com/c/toolchain/llvm_android/+/1965517 has the cherry-pick for r416183b (but needs prebuilts once merged).

[DanAlbert]

Should be fixed in build 8486889.