https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99269
Bug ID: 99269
Summary: False positive
-Wanalyzer-malloc-leak/-Wanalyzer-double-free with
-fanalyzer
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: vmjuan90 at gmail dot com
Target Milestone: ---
Created attachment 50255
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50255&action=edit
minimun example for reproduce
Hello
I added the minimun example file (bug.c) and the gcc command line for reproduce
what i think are 2 false positives from -fanalizer
$ gcc -v -save-temps -fanalyzer -c bug.c
Usando especificaciones internas.
COLLECT_GCC=gcc
Objetivo: x86_64-pc-linux-gnu
Configurado con:
/var/tmp/portage/sys-devel/gcc-10.2.0-r5/work/gcc-10.2.0/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/10.2.0
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/10.2.0
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/10.2.0/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/10.2.0/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include/g++-v10
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/10.2.0/python
--enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt
--disable-werror --with-system-zlib --enable-nls --without-included-gettext
--enable-checking=release --with-bugurl=https://bugs.gentoo.org/
--with-pkgversion='Gentoo 10.2.0-r5 p6' --disable-esp --enable-libstdcxx-time
--with-build-config=bootstrap-lto --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu --enable-multilib
--with-multilib-list=m32,m64 --disable-fixed-point --enable-targets=all
--enable-libgomp --disable-libssp --disable-libada --disable-systemtap
--enable-vtable-verify --without-zstd --enable-lto --with-isl
--disable-isl-version-check --enable-default-pie --enable-default-ssp
Modelo de hilos: posix
Algoritmos de compresión LTO admitidos: zlib
gcc versión 10.2.0 (Gentoo 10.2.0-r5 p6)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-fanalyzer' '-c' '-mtune=generic'
'-march=x86-64'
/usr/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/cc1 -E -quiet -v bug.c
-mtune=generic -march=x86-64 -fanalyzer -fpch-preprocess -o bug.i
se descarta el directorio inexistente "/usr/local/include"
se descarta el directorio inexistente
"/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../x86_64-pc-linux-gnu/include"
la búsqueda de #include "..." inicia aquí:
la búsqueda de #include <...> inicia aquí:
/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include
/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include-fixed
/usr/include
Fin de la lista de búsqueda.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-fanalyzer' '-c' '-mtune=generic'
'-march=x86-64'
/usr/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/cc1 -fpreprocessed bug.i -quiet
-dumpbase bug.c -mtune=generic -march=x86-64 -auxbase bug -version -fanalyzer
-o bug.s
GNU C17 (Gentoo 10.2.0-r5 p6) versión 10.2.0 (x86_64-pc-linux-gnu)
compilado por GNU C versión 10.2.0, GMP versión 6.2.1, MPFR versión
4.1.0, MPC versión 1.2.1, isl versión isl-0.23-GMP
GGC heurísticas: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C17 (Gentoo 10.2.0-r5 p6) versión 10.2.0 (x86_64-pc-linux-gnu)
compilado por GNU C versión 10.2.0, GMP versión 6.2.1, MPFR versión
4.1.0, MPC versión 1.2.1, isl versión isl-0.23-GMP
GGC heurísticas: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 5fe470a537c6a646ee2db89927c9a5b2
En la función ‘example’:
bug.c:11:10: aviso: leak of ‘<desconocido>’ [CWE-401] [-Wanalyzer-malloc-leak]
11 | namelist[1] = malloc(sizeof **namelist);
| ^
‘example’: events 1-6
|
| 9 | if (!namelist) return;
| | ^
| | |
| | (1) following ‘false’ branch (when ‘namelist’ is non-NULL)...
| 10 | namelist[0] = malloc(sizeof **namelist);
| | ~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (2) ...to here
| | (3) allocated here
| 11 | namelist[1] = malloc(sizeof **namelist);
| | ~
| | |
| | (6) ‘<desconocido>’ leaks here; was allocated at (3)
| 12 |
| 13 | while(len--) { free(namelist[len]); }
| | ~ ~
| | | |
| | | (5) ...to here
| | (4) following ‘true’ branch...
|
bug.c:13:17: aviso: double-‘free’ of ‘<desconocido>’ [CWE-415]
[-Wanalyzer-double-free]
13 | while(len--) { free(namelist[len]); }
| ^~~~~~~~~~~~~~~~~~~
‘example’: events 1-11
|
| 9 | if (!namelist) return;
| | ^
| | |
| | (1) following ‘false’ branch (when ‘namelist’ is non-NULL)...
| 10 | namelist[0] = malloc(sizeof **namelist);
| | ~~~~~~~~~~~~~~~~~~~~~~~~~
| | |
| | (2) ...to here
|......
| 13 | while(len--) { free(namelist[len]); }
| | ~ ~~~~~~~~~~~~~~~~~~~
| | | | |
| | | | (4) ...to here
| | | | (5) first ‘free’ here
| | | | (7) ...to here
| | | | (8) first ‘free’ here
| | | | (10) ...to here
| | | (11) second ‘free’ here; first ‘free’ was at (8)
| | (3) following ‘true’ branch...
| | (6) following ‘true’ branch...
| | (9) following ‘true’ branch...
|
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-fanalyzer' '-c' '-mtune=generic'
'-march=x86-64'
/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../x86_64-pc-linux-gnu/bin/as
-v --64 -o bug.o bug.s
GNU ensamblador versión 2.34.0 (x86_64-pc-linux-gnu) utilizando BFD versión
(Gentoo 2.34 p6) 2.34.0
COMPILER_PATH=/usr/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/:/usr/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/:/usr/libexec/gcc/x86_64-pc-linux-gnu/:/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/:/usr/lib/gcc/x86_64-pc-linux-gnu/:/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../x86_64-pc-linux-gnu/bin/
LIBRARY_PATH=/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/:/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../x86_64-pc-linux-gnu/lib/:/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-fanalyzer' '-c' '-mtune=generic'
'-march=x86-64'
regards
