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* [Bug stdio/28828] New: fputwc crashes
@ 2022-01-27 13:01 jobol at nonadev dot net
2022-01-27 13:04 ` [Bug stdio/28828] " jobol at nonadev dot net
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: jobol at nonadev dot net @ 2022-01-27 13:01 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=28828
Bug ID: 28828
Summary: fputwc crashes
Product: glibc
Version: 2.33
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: stdio
Assignee: unassigned at sourceware dot org
Reporter: jobol at nonadev dot net
Target Milestone: ---
Created attachment 13933
--> https://sourceware.org/bugzilla/attachment.cgi?id=13933&action=edit
short program
on amd64, debian.
the program b.c attached (and listed below). Crashes with SIGSEGV in the first
fputwc.
It does not crashes if I comment the line 8.
1: #include <stdio.h>
2: #include <wchar.h>
3: int main(int ac, char **av)
4: {
5: wint_t c;
6:
7: setvbuf(stdin, NULL, _IOLBF, 0);
8: setvbuf(stdout, NULL, _IOLBF, 0);
9: c = fgetwc(stdin);
10: fputwc(c, stdout);
11: fputwc(10, stdout);
12: return 0;
13: }
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* [Bug stdio/28828] fputwc crashes
2022-01-27 13:01 [Bug stdio/28828] New: fputwc crashes jobol at nonadev dot net
@ 2022-01-27 13:04 ` jobol at nonadev dot net
2022-03-08 17:26 ` cvs-commit at gcc dot gnu.org
2022-03-08 17:27 ` adhemerval.zanella at linaro dot org
2 siblings, 0 replies; 4+ messages in thread
From: jobol at nonadev dot net @ 2022-01-27 13:04 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=28828
--- Comment #1 from José Bollo <jobol at nonadev dot net> ---
also, when I insert "fputwc(10, stdout);" between lines 8 and 9, the crash does
not happen.
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* [Bug stdio/28828] fputwc crashes
2022-01-27 13:01 [Bug stdio/28828] New: fputwc crashes jobol at nonadev dot net
2022-01-27 13:04 ` [Bug stdio/28828] " jobol at nonadev dot net
@ 2022-03-08 17:26 ` cvs-commit at gcc dot gnu.org
2022-03-08 17:27 ` adhemerval.zanella at linaro dot org
2 siblings, 0 replies; 4+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2022-03-08 17:26 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=28828
--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Adhemerval Zanella
<azanella@sourceware.org>:
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=edc696a73a7cb07b1aa68792a845a98d036ee7eb
commit edc696a73a7cb07b1aa68792a845a98d036ee7eb
Author: José Bollo <jobol@nonadev.net>
Date: Tue Mar 8 09:58:16 2022 +0100
libio: Ensure output buffer for wchars (bug #28828)
The _IO_wfile_overflow does not check if the write pointer for wide
data is valid before access, different than _IO_file_overflow. This
leads to crash on some cases, as described by bug 28828.
The minimal sequence to produce the crash was:
#include <stdio.h>
#include <wchar.h>
int main (int ac, char **av)
{
setvbuf (stdout, NULL, _IOLBF, 0);
fgetwc (stdin);
fputwc (10, stdout); /*CRASH HERE!*/
return 0;
}
The "fgetwc(stdin);" is necessary since it triggers the bug by setting
the flag _IO_CURRENTLY_PUTTING on stdout indirectly (file wfileops.c,
function _IO_wfile_underflow, line 213).
Signed-off-by: Jose Bollo <jobol@nonadev.net>
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* [Bug stdio/28828] fputwc crashes
2022-01-27 13:01 [Bug stdio/28828] New: fputwc crashes jobol at nonadev dot net
2022-01-27 13:04 ` [Bug stdio/28828] " jobol at nonadev dot net
2022-03-08 17:26 ` cvs-commit at gcc dot gnu.org
@ 2022-03-08 17:27 ` adhemerval.zanella at linaro dot org
2 siblings, 0 replies; 4+ messages in thread
From: adhemerval.zanella at linaro dot org @ 2022-03-08 17:27 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=28828
Adhemerval Zanella <adhemerval.zanella at linaro dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |adhemerval.zanella at linaro dot o
| |rg
Target Milestone|--- |2.36
Resolution|--- |FIXED
Status|UNCONFIRMED |RESOLVED
--- Comment #3 from Adhemerval Zanella <adhemerval.zanella at linaro dot org> ---
Fixed on 2.36.
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2022-01-27 13:01 [Bug stdio/28828] New: fputwc crashes jobol at nonadev dot net
2022-01-27 13:04 ` [Bug stdio/28828] " jobol at nonadev dot net
2022-03-08 17:26 ` cvs-commit at gcc dot gnu.org
2022-03-08 17:27 ` adhemerval.zanella at linaro dot org
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