From: Bruno Haible <bruno@clisp.org>
To: "Tim Rühsen" <tim.ruehsen@gmx.de>
Cc: bug-gnulib@gnu.org
Subject: SA_RESETHAND
Date: Thu, 21 May 2020 17:15:38 +0200 [thread overview]
Message-ID: <1914708.U9Lh6kAjoy@omega> (raw)
In-Reply-To: <e97c6577-7167-2b02-8b67-8e1a63701811@gmx.de>
Tim Rühsen reports:
> configure:14038: checking for working C stack overflow detection
> SUMMARY: UndefinedBehaviorSanitizer: implicit-integer-sign-change
Here's a reduced test case:
$ cat foo.c
#include <signal.h>
int
main ()
{
struct sigaction act;
act.sa_flags = /* SA_NODEFER | SA_ONSTACK | */ SA_RESETHAND;
return 0;
}
$ clang -Wall foo.c -E | grep sa_flags
int sa_flags;
act.sa_flags = 0x80000000;
$ clang -Wall foo.c -fsanitize=implicit-integer-sign-change
$ ./a.out
foo.c:7:50: runtime error: implicit conversion from type 'unsigned int' of value 2147483648 (32-bit, unsigned) to type 'int' changed the value to -2147483648 (32-bit, signed)
So, glibc defines the 'sa_flags' field as being of type 'int' (like
POSIX [1] mandates). glibc also defines SA_RESETHAND as 0x80000000.
The compiler interprets this constant as being of type 'unsigned int'.
The sanitizer then complains about an implicit conversion from 'unsigned int'
to 'int'.
How to resolve this?
- Should glibc define SA_RESETHAND as ((int)0x80000000) ?
Then SA_RESETHAND could not be used in preprocessor directives any more.
- Should clang be silent about this case of implicit conversion?
- Should we discourage users from using -fsanitize=implicit-integer-sign-change?
Bruno
[1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/sigaction.html
next prev parent reply other threads:[~2020-05-21 15:15 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-18 10:43 Fix memleak in getdelim.m4 Tim Rühsen
2020-05-18 11:50 ` Bruno Haible
2020-05-18 18:21 ` Tim Rühsen
2020-05-18 19:44 ` Bruno Haible
2020-05-19 21:47 ` Tim Rühsen
2020-05-19 22:46 ` Bruno Haible
2020-05-20 18:45 ` Tim Rühsen
2020-05-21 14:22 ` relicense module 'group-member' Bruno Haible
2020-05-21 14:44 ` Eric Blake
2020-05-21 15:10 ` Jim Meyering
2020-05-21 19:46 ` Bruno Haible
2020-05-21 19:27 ` Paul Eggert
2020-05-21 14:23 ` Fix memleak in getdelim.m4 Bruno Haible
2020-05-20 21:59 ` Tim Rühsen
2020-05-21 14:26 ` Bruno Haible
2020-05-21 16:11 ` Tim Rühsen
2020-05-21 19:31 ` Bruno Haible
2020-05-22 14:03 ` Tim Rühsen
2020-05-22 15:25 ` Bruno Haible
2020-05-22 20:46 ` Tim Rühsen
2020-05-23 17:51 ` Fix exponentl.m4 test Bruno Haible
2020-05-23 18:48 ` Fix calloc.m4 test Bruno Haible
2020-05-23 20:26 ` Paul Eggert
2020-05-23 21:53 ` Bruno Haible
2020-05-24 0:51 ` Paul Eggert
2020-05-24 7:53 ` Bruno Haible
2020-06-06 8:19 ` Bruno Haible
2020-05-23 19:18 ` Fix invalid use of __builtin_isnanf and __builtin_isnanl Bruno Haible
2020-05-23 20:18 ` Fix calloc-gnu configure results Bruno Haible
2020-05-23 20:47 ` Fix memleak in getdelim.m4 Bruno Haible
2020-05-24 8:39 ` Tim Rühsen
2020-05-21 15:15 ` Bruno Haible [this message]
2020-05-21 20:10 ` SA_RESETHAND Paul Eggert
2020-05-21 20:59 ` SA_RESETHAND Bruno Haible
2020-05-21 15:22 ` Fix sanitizer error in fchownat.m4 Bruno Haible
2020-05-21 17:42 ` Fix memleak in glob.m4 Bruno Haible
2020-05-21 18:31 ` Fix memleak in regex.m4 Bruno Haible
2020-05-21 18:40 ` Fix memleak in getdelim.m4 Bruno Haible
2020-05-21 19:30 ` Paul Eggert
2020-05-21 19:38 ` Bruno Haible
2020-05-21 14:32 ` Bruno Haible
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