[R-pkg-devel] R session crash on closing a graphic device on Windows

[Hiroaki Yutani]

Hi Tomas,

Thanks for your helpful advice. This time, it seems the cause of the
error was an allocator mismatch; I mistakenly allocated the struct on
Rust's side, which means it's allocated by Rust's allocator, but a
`DevDesc` is to be freed on R's side. The problem is solved by using
libc::calloc(), which allocates using the C runtime's allocator, and
compiling it with the same toolchain that compiles R.

I also saw some errors when it relates to GC, so it might be some
PROTECT issue. Thanks for the hint.

During debugging, I learned a lot about how to build R with DEBUG=T
and use gdb, and it really helped me. I'm yet to unlock the power of
WinDBG, but I will try next time...

Best,
Yutani

2022年1月26日(水) 23:20 Tomas Kalibera <tomas.kalibera using gmail.com>:

>
> Hi Yutani,
>
> if you haven't done that already, I would recommend building R with
> debug symbols (DEBUG=T, so that make file don't strip them) and with -O0
> (no optimizations), so that the debug symbols are more accurate. Without
> that, the stack traces can be very misleading. You might try both with
> windbg and gdb, sometimes one of them provides an extra hint. Ideally
> you would also build the involved package(s) the same way.
>
> Then, it is important to check where the free() is called from, whether
> it is directly or from the GC. In both cases (but more likely in the
> latter), it could be caused by somewhat unrelated memory corruption,
> which may be hard to find - e.g. possibly a PROTECT error. Running with
> gctorture() might help, if gctorture() changes where the crash happens,
> it is more likely a somewhat unrelated memory corruption.
>
> If it were a double-free or similar allocation error inside R itself (or
> some of the involved packages), it would be easy to find with a debugger.
>
> If debugging this way does not help, you can try narrowing down the
> example, while preserving the crash. That may make debugging easier, and
> if you eventually get to a point that you have a reproducible example
> involving only base R and base packages, you know it is a bug in R, and
> can submit that in a bug report for others to debug.
>
> Best
> Tomas
>
> On 1/22/22 10:50, Hiroaki Yutani wrote:
> > Hi,
> >
> > I'm trying to create a Rust library that can implement an R graphic
> > device[1], but the R session crashes on `dev.off()` on Windows with R
> > 4.1.2. Strangely, it works without errors on Linux, on macOS, and even
> > on Windows with R-devel.
> >
> > Looking at the stack trace below by WinDbg, the problem is probably
> > that either of the two free()s in GEdestroyDevDesc() tries to free
> > some memory that was already freed (I'm a very beginner of this kind
> > of debugging, so I might be wrong).
> >
> >      # Child-SP          RetAddr               Call Site
> >      00 00000000`0441cb70 00007ffb`3df0be63     ntdll!RtlReportFatalFailure+0x9
> >      01 00000000`0441cbc0 00007ffb`3df14c82
> > ntdll!RtlReportCriticalFailure+0x97
> >      ...snip...
> >      08 00000000`0441cfc0 00007ffb`3c30c6ac     ntdll!RtlFreeHeap+0x51
> >      09 00000000`0441d000 00000000`6c7bcf99     msvcrt!free+0x1c
> >      0a 00000000`0441d030 00000000`6c79e7de     R!GEdestroyDevDesc+0x59
> >      0b 00000000`0441d080 00000000`6fc828e9     R!GEcurrentDevice+0x37e
> >      0c 00000000`0441d0f0 00000000`6c7a15fa     grDevices!devoff+0x59
> >      ...snip...
> >
> > But, I found no difference in the related code (around devoff() and
> > GEdestroyDevDesc()) between R 4.1.2 and R-devel. I know there are a
> > lot of feature additions in R-devel, but I don't think it affects
> > here. Is there anyone who suffered from similar crashes? Am I missing
> > something?
> >
> > I would appreciate any advice.
> >
> > Best,
> > Yutani
> >
> > [1]: https://github.com/extendr/extendr/pull/360
> >
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