The following changes were made in the btf_parse_elf function:
1. The initialization assignments of err, fd, scn and elf variables are
removed, and they do not affect function security after analysis.
2. Remove unnecessary assignments to err variable (-error).
Signed-off-by: Li kunyu <[email protected]>
---
tools/lib/bpf/btf.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 2d14f1a52d7a..fa9d5fa03da4 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -910,10 +910,10 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
struct btf_ext **btf_ext)
{
Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
- int err = 0, fd = -1, idx = 0;
+ int err, fd, idx = 0;
struct btf *btf = NULL;
- Elf_Scn *scn = NULL;
- Elf *elf = NULL;
+ Elf_Scn *scn;
+ Elf *elf;
GElf_Ehdr ehdr;
size_t shstrndx;
@@ -924,9 +924,8 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
fd = open(path, O_RDONLY | O_CLOEXEC);
if (fd < 0) {
- err = -errno;
pr_warn("failed to open %s: %s\n", path, strerror(errno));
- return ERR_PTR(err);
+ return ERR_PTR(-errno);
}
err = -LIBBPF_ERRNO__FORMAT;
@@ -987,8 +986,6 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
}
}
- err = 0;
-
if (!btf_data) {
err = -ENOENT;
goto done;
--
2.18.2
Hi Li,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on bpf-next/master]
[also build test ERROR on bpf/master linus/master v6.0 next-20221007]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Li-kunyu/lib-bpf-Optimized-variable-usage-in-the-btf_parse_elf-function/20221008-162305
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: s390-defconfig
compiler: s390-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/74268712be9dbfe27fbf4d9b313f88e3f7e7cf0f
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Li-kunyu/lib-bpf-Optimized-variable-usage-in-the-btf_parse_elf-function/20221008-162305
git checkout 74268712be9dbfe27fbf4d9b313f88e3f7e7cf0f
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=s390 prepare
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings
All errors (new ones prefixed by >>):
scripts/genksyms/parse.y: warning: 9 shift/reduce conflicts [-Wconflicts-sr]
scripts/genksyms/parse.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
scripts/genksyms/parse.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
btf.c: In function 'btf_parse_elf':
>> btf.c:954:23: error: 'scn' may be used uninitialized [-Werror=maybe-uninitialized]
954 | while ((scn = elf_nextscn(elf, scn)) != NULL) {
| ^~~~~~~~~~~~~~~~~~~~~
btf.c:915:18: note: 'scn' was declared here
915 | Elf_Scn *scn;
| ^~~
cc1: all warnings being treated as errors
make[5]: *** [tools/build/Makefile.build:96: tools/bpf/resolve_btfids/libbpf/staticobjs/btf.o] Error 1
make[5]: *** Waiting for unfinished jobs....
make[4]: *** [Makefile:157: tools/bpf/resolve_btfids/libbpf/staticobjs/libbpf-in.o] Error 2
make[3]: *** [Makefile:55: tools/bpf/resolve_btfids//libbpf/libbpf.a] Error 2
make[2]: *** [Makefile:76: bpf/resolve_btfids] Error 2
make[1]: *** [Makefile:1423: tools/bpf/resolve_btfids] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:231: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.
--
0-DAY CI Kernel Test Service
https://01.org/lkp
Hi Li,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on bpf-next/master]
[also build test ERROR on bpf/master linus/master v6.0 next-20221007]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Li-kunyu/lib-bpf-Optimized-variable-usage-in-the-btf_parse_elf-function/20221008-162305
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: x86_64-rhel-8.3-kselftests
compiler: gcc-11 (Debian 11.3.0-5) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/74268712be9dbfe27fbf4d9b313f88e3f7e7cf0f
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Li-kunyu/lib-bpf-Optimized-variable-usage-in-the-btf_parse_elf-function/20221008-162305
git checkout 74268712be9dbfe27fbf4d9b313f88e3f7e7cf0f
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=x86_64 prepare
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>
Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings
All errors (new ones prefixed by >>):
btf.c: In function 'btf_parse_elf':
>> btf.c:954:23: error: 'scn' may be used uninitialized in this function [-Werror=maybe-uninitialized]
954 | while ((scn = elf_nextscn(elf, scn)) != NULL) {
| ^~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[5]: *** [tools/build/Makefile.build:96: tools/bpf/resolve_btfids/libbpf/staticobjs/btf.o] Error 1
make[5]: *** Waiting for unfinished jobs....
make[4]: *** [Makefile:157: tools/bpf/resolve_btfids/libbpf/staticobjs/libbpf-in.o] Error 2
make[3]: *** [Makefile:55: tools/bpf/resolve_btfids//libbpf/libbpf.a] Error 2
make[2]: *** [Makefile:76: bpf/resolve_btfids] Error 2
make[1]: *** [Makefile:1422: tools/bpf/resolve_btfids] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:231: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.
--
0-DAY CI Kernel Test Service
https://01.org/lkp
The following changes were made in the btf_parse_elf function:
1. The initialization assignments of err, fd, scn and elf variables are
removed, and they do not affect function security after analysis.
2. Remove unnecessary assignments to err variable (-error).
Signed-off-by: Li kunyu <[email protected]>
---
tools/lib/bpf/btf.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 2d14f1a52d7a..fa9d5fa03da4 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -910,10 +910,10 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
struct btf_ext **btf_ext)
{
Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
- int err = 0, fd = -1, idx = 0;
+ int err, fd, idx = 0;
struct btf *btf = NULL;
- Elf_Scn *scn = NULL;
- Elf *elf = NULL;
+ Elf_Scn *scn;
+ Elf *elf;
GElf_Ehdr ehdr;
size_t shstrndx;
@@ -924,9 +924,8 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
fd = open(path, O_RDONLY | O_CLOEXEC);
if (fd < 0) {
- err = -errno;
pr_warn("failed to open %s: %s\n", path, strerror(errno));
- return ERR_PTR(err);
+ return ERR_PTR(-errno);
}
err = -LIBBPF_ERRNO__FORMAT;
@@ -987,8 +986,6 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
}
}
- err = 0;
-
if (!btf_data) {
err = -ENOENT;
goto done;
--
2.18.2
Hello, I use the main line code (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git）The compilation can be successful according to the compilation instructions you provided (at present, it is unclear why the bpf repository compiles warnings and compilation fails). Later, I will deploy a new repository and try to compile again.
Hello, I use the main line code（ https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git ）The compilation can be successful according to the compilation instructions you provided (at present, it is unclear why the bpf repository compiles warnings and compilation fails). Later, I will deploy a new repository and try to compile again.
After writing the reply message, press 'e' to edit the message, and the result is sent to the patch file.....
On Sun, Oct 09, 2022 at 03:08:28PM +0800, Li kunyu wrote:
> The following changes were made in the btf_parse_elf function:
> 1. The initialization assignments of err, fd, scn and elf variables are
> removed, and they do not affect function security after analysis.
> 2. Remove unnecessary assignments to err variable (-error).
>
> Signed-off-by: Li kunyu <[email protected]>
> ---
> tools/lib/bpf/btf.c | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index 2d14f1a52d7a..fa9d5fa03da4 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -910,10 +910,10 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
> struct btf_ext **btf_ext)
> {
> Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
> - int err = 0, fd = -1, idx = 0;
> + int err, fd, idx = 0;
> struct btf *btf = NULL;
> - Elf_Scn *scn = NULL;
> - Elf *elf = NULL;
> + Elf_Scn *scn;
> + Elf *elf;
> GElf_Ehdr ehdr;
> size_t shstrndx;
>
> @@ -924,9 +924,8 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
>
> fd = open(path, O_RDONLY | O_CLOEXEC);
> if (fd < 0) {
> - err = -errno;
> pr_warn("failed to open %s: %s\n", path, strerror(errno));
> - return ERR_PTR(err);
> + return ERR_PTR(-errno);
hum, pr_warn could potentionally change errno
jirka
> }
>
> err = -LIBBPF_ERRNO__FORMAT;
> @@ -987,8 +986,6 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
> }
> }
>
> - err = 0;
> -
> if (!btf_data) {
> err = -ENOENT;
> goto done;
> --
> 2.18.2
>