bug#55832: 28.1; Emacs crashes when using tramp from helm in emacs-29

[Thierry Volpiatto]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Thierry Volpiatto <thievol@posteo.net>
>> Date: Tue, 07 Jun 2022 15:16:36 +0000
>> 
>> 
>> I can't reproduce from emacs -Q using M-x find-file, but the bug happens
>> with Helm when using M-x helm-find-files /sudo::
>> Emacs freeze and then in gdb:
>> 
>>     Thread 1 "emacs" received signal SIGSEGV, Segmentation fault.
>>     0x0000555555837be7 in doprnt.part ()
>> 
>> In all previous emacs this worked normally, working fine here in
>> emacs-28.1.
>> This is a followup of bug #55555.
>> 
>> I can send more infos from gdb if you give me instructions, I tried bt
>> but the output is huge.
>
> The first step is to figure out what was the immediate reason for the
> segfault, and in which source line it happened.
>
> Your build is heavily optimized, so I suggest to rebuild with the
> following additional compiler options:
>
>    -gdwarf-4 -g3

I have now rebuilded with:

./configure CFLAGS='-08 -gdwarf-4 -g3' --with-native-compilation

First try with /sudo:: I couldn't reproduce, then I waited the
native-compilation fully finish and could reproduce.

When fixing other warnings this morning I saw this warning in *Warnings*
buffer:

/usr/local/share/emacs/site-lisp/helm/helm-files.el: Error: Wrong type
argument sequencep

But couldn't figure out what is this error, I have no error or warnings
when compiling and everything work fine in emacs-28, don't know if this
could be related to this crash.

> Then run Emacs under GDB, and when it crashes, type
>
>   (gdb) thread 1
>   (gdb) bt -full 5
>
> and post the results.

[...]
[Detaching after vfork from child process 229481]

Thread 1 "emacs" received signal SIGSEGV, Segmentation fault.
0x0000555555837be7 in doprnt (buffer=0x7fffff6702c0 "", bufsize=4000, 
format=0x5555558af29a "Bytecode stack overflow", ap=0x7fffff670250, 
format_end=<optimized out>) at doprnt.c:186
186     doprnt (char *buffer, ptrdiff_t bufsize, const char *format,
(gdb) thread 1
[Switching to thread 1 (Thread 0x7ffff07ce3c0 (LWP 226687))]
#0  0x0000555555837be7 in doprnt (buffer=0x7fffff6702c0 "", bufsize=4000, 
format=0x5555558af29a "Bytecode stack overflow", ap=0x7fffff670250, 
format_end=<optimized out>) at doprnt.c:186
186     doprnt (char *buffer, ptrdiff_t bufsize, const char *format,
(gdb) bt -full 5
#0  0x0000555555837be7 in doprnt (buffer=0x7fffff6702c0 "", bufsize=4000, 
format=0x5555558af29a "Bytecode stack overflow", ap=0x7fffff670250, 
format_end=<optimized out>) at doprnt.c:186
        fmt = <optimized out>
        bufptr = <optimized out>
        tembuf = '\000' <repeats 407 times>
        size_allocated = <optimized out>
        sprintf_buffer = <optimized out>
        big_buffer = <optimized out>
        quoting_style = <optimized out>
#1  0x0000555555838a57 in doprnt (ap=0x7fffff670250, format_end=0x0, 
format=0x5555558af29a "Bytecode stack overflow", bufsize=<optimized out>, 
buffer=<optimized out>) at doprnt.c:590
        modifier_len = "\000\001\001\001\001"
        nbytes = <optimized out>
        ap_copy = {{gp_offset = 8, fp_offset = 48, overflow_arg_area = 
0x7fffff671380, reg_save_area = 0x7fffff6712c0}}
#2  evxprintf
    (buf=buf@entry=0x7fffff6702b8, bufsize=bufsize@entry=0x7fffff6702b0, 
nonheapbuf=nonheapbuf@entry=0x7fffff6702c0 "", 
bufsize_max=bufsize_max@entry=2305843009213693952, format=0x5555558af29a 
"Bytecode stack overflow", ap=ap@entry=0x7fffff6712a0) at doprnt.c:590
        nbytes = <optimized out>
        ap_copy = {{gp_offset = 8, fp_offset = 48, overflow_arg_area = 
0x7fffff671380, reg_save_area = 0x7fffff6712c0}}
#3  0x00005555557aa5f3 in vformat_string (m=<optimized out>, 
ap=ap@entry=0x7fffff6712a0) at eval.c:2029
        buf = '\000' <repeats 409 times>...
        size = 4000
        buffer = 0x7fffff6702c0 ""
        used = <optimized out>
        string = <optimized out>
#4  0x00005555555aac6f in verror (m=<optimized out>, 
ap=ap@entry=0x7fffff6712a0) at eval.c:2041
(More stack frames follow...)


-- 
Thierry

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