bug#42657: emacs-27.1-rc1 and Asan findings

bug#42657: emacs-27.1-rc1 and Asan findings

[Jeffrey Walton]

I don't have log files for Asan testing. The process is killed before
the log file gets written.

I think just about every test failed similar to:

=================================================================
==18430==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 16 byte(s) in 1 object(s) allocated from:
    #0 0x7f4408236d28 in __interceptor_calloc
(/usr/lib/x86_64-linux-gnu/libasan.so.4+0xded28)
    #1 0x56126c6f40a5 in dump_mmap_contiguous_heap
/home/jwalton/Build-Scripts/emacs-27.1/src/pdumper.c:4684
    #2 0x56126c6f40a5 in dump_mmap_contiguous
/home/jwalton/Build-Scripts/emacs-27.1/src/pdumper.c:4868
    #3 0x56126c6f40a5 in pdumper_load
/home/jwalton/Build-Scripts/emacs-27.1/src/pdumper.c:5428
    #4 0x56126c47e1d2 in load_pdump
/home/jwalton/Build-Scripts/emacs-27.1/src/emacs.c:853
    #5 0x56126c47e1d2 in main
/home/jwalton/Build-Scripts/emacs-27.1/src/emacs.c:1062
    #6 0x7f4406512b96 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x21b96)

SUMMARY: AddressSanitizer: 16 byte(s) leaked in 1 allocation(s).

bug#42657: emacs-27.1-rc1 and Asan findings

[Philipp Stephani]

Am Sa., 1. Aug. 2020 um 22:24 Uhr schrieb Jeffrey Walton <noloader@gmail.com>:
>
> I don't have log files for Asan testing. The process is killed before
> the log file gets written.
>
> I think just about every test failed similar to:
>
> =================================================================
> ==18430==ERROR: LeakSanitizer: detected memory leaks


Emacs intentionally leaks a lot of memory (like every system with a
GC), so those tend to be false positives. If they still happen on
master, consider suppressing them using __lsan_ignore_object or
similar.

bug#42657: emacs-27.1-rc1 and Asan findings

[Jeffrey Walton]

On Sat, Aug 1, 2020 at 4:32 PM Philipp Stephani <p.stephani2@gmail.com> wrote:
>
> Am Sa., 1. Aug. 2020 um 22:24 Uhr schrieb Jeffrey Walton <noloader@gmail.com>:
> >
> > I don't have log files for Asan testing. The process is killed before
> > the log file gets written.
> >
> > I think just about every test failed similar to:
> >
> > =================================================================
> > ==18430==ERROR: LeakSanitizer: detected memory leaks
>
>
> Emacs intentionally leaks a lot of memory (like every system with a
> GC), so those tend to be false positives. If they still happen on
> master, consider suppressing them using __lsan_ignore_object or
> similar.

How does one tell the good leaks from the bad leaks?

Jeff

bug#42657: emacs-27.1-rc1 and Asan findings

[Paul Eggert]

> How does one tell the good leaks from the bad leaks?

In Emacs 27 please don't bother, as nobody had gotten around to marking leaks. 
Since this bug report is about Emacs 27 I'm taking the liberty of closing it.

In the master branch we have marked leaks. I just built it with ./configure 
CC='gcc -fsanitize=address' and 'make check' worked for me on Fedora 31 x86-64. 
If you find a leak I suggest deciding whether the leak is worth worrying about 
and then either plugging the leak or marking it as OK.