https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111513
Bug ID: 111513
Summary: Incorrect -Wformat-overflow warning when using UBSAN
with gettext()
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: g...@t-8ch.de
CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxin at
gcc dot gnu.org
Target Milestone: ---
Created attachment 55957
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55957&action=edit
preprocessed source
The test program below exhibits the following compiler warning:
test.c: In function ‘main’:
test.c:14:9: warning: null format string [-Wformat-overflow=]
14 | printf(gettext("foo %s\n"), "foo");
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test.c:14:9: warning: null format string [-Wformat-overflow=]
/* test.c
*
* compile with:
* gcc -Wall -fsanitize=undefined -O2 test.c
*/
#include <stdio.h>
#include <libintl.h>
int main(void)
{
FILE *out = stdout;
fputs("\n", out);
printf(gettext("foo %s\n"), "foo");
fputs("\n", out);
}
The warning can be "fixed" by *any* of the following steps:
* remove any of the fputs() calls
* inline the stdout parameter into the second fputs() call
* build without optimizations
* build without UBSAN
Given the weirdness with regards to the fputs() calls I suspect the issue in
GCC.
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/13.2.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure
--enable-languages=ada,c,c++,d,fortran,go,lto,objc,obj-c++ --enable-bootstrap
--prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/
--with-build-config=bootstrap-lto --with-linker-hash-style=gnu
--with-system-zlib --enable-__cxa_atexit --enable-cet=auto
--enable-checking=release --enable-clocale=gnu --enable-default-pie
--enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object
--enable-libstdcxx-backtrace --enable-link-serialization=1
--enable-linker-build-id --enable-lto --enable-multilib --enable-plugin
--enable-shared --enable-threads=posix --disable-libssp --disable-libstdcxx-pch
--disable-werror
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 13.2.1 20230801 (GCC)
glibc version: 2.38
