[bpf-next] selftests/bpf: Fix strncpy() fortify warning
Commit Message
From: Rong Tao <rongtao@cestc.cn>
move libbpf_strlcpy() to bpf_util.h, and replace strncpy() with
libbpf_strlcpy(), fix compile warning.
Compile samples/bpf, warning:
$ cd samples/bpf
$ make
...
cgroup_helpers.c: In function ‘__enable_controllers’:
cgroup_helpers.c:80:17: warning: ‘strncpy’ specified bound 4097 equals destination size [-Wstringop-truncation]
80 | strncpy(enable, controllers, sizeof(enable));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Rong Tao <rongtao@cestc.cn>
---
tools/testing/selftests/bpf/bpf_util.h | 19 +++++++++++++++++++
tools/testing/selftests/bpf/cgroup_helpers.c | 3 ++-
tools/testing/selftests/bpf/xsk.c | 20 +-------------------
3 files changed, 22 insertions(+), 20 deletions(-)
Comments
On 11/1/22 3:23 PM, Rong Tao wrote:
> From: Rong Tao <rongtao@cestc.cn>
>
> move libbpf_strlcpy() to bpf_util.h, and replace strncpy() with
> libbpf_strlcpy(), fix compile warning.
>
> Compile samples/bpf, warning:
> $ cd samples/bpf
> $ make
> ...
> cgroup_helpers.c: In function ‘__enable_controllers’:
> cgroup_helpers.c:80:17: warning: ‘strncpy’ specified bound 4097 equals destination size [-Wstringop-truncation]
> 80 | strncpy(enable, controllers, sizeof(enable));
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Signed-off-by: Rong Tao <rongtao@cestc.cn>
Nope, BPF CI fails once again with:
https://github.com/kernel-patches/bpf/actions/runs/3370230622/jobs/5590876906
[...]
TEST-OBJ [test_progs-no_alu32] connect_ping.test.o
TEST-OBJ [test_progs-no_alu32] map_kptr.test.o
In file included from /tmp/work/bpf/bpf/tools/testing/selftests/bpf/prog_tests/perf_branches.c:7:
/tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/include/bpf/libbpf_internal.h:200:20: error: redefinition of 'libbpf_strlcpy'
static inline void libbpf_strlcpy(char *dst, const char *src, size_t sz)
^
/tmp/work/bpf/bpf/tools/testing/selftests/bpf/bpf_util.h:29:20: note: previous definition is here
static inline void libbpf_strlcpy(char *dst, const char *src, size_t sz)
^
1 error generated.
TEST-OBJ [test_progs-no_alu32] hash_large_key.test.o
make: *** [Makefile:539: /tmp/work/bpf/bpf/tools/testing/selftests/bpf/no_alu32/perf_branches.test.o] Error 1
make: *** Waiting for unfinished jobs....
make: Leaving directory '/tmp/work/bpf/bpf/tools/testing/selftests/bpf'
Error: Process completed with exit code 2.
Please do not send broken stuff that was not even compile tested.
Here's a small howto for running BPF selftests:
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/tree/tools/testing/selftests/bpf/README.rst#n48
@@ -20,6 +20,25 @@ static inline unsigned int bpf_num_possible_cpus(void)
return possible_cpus;
}
+/* Copy up to sz - 1 bytes from zero-terminated src string and ensure that dst
+ * is zero-terminated string no matter what (unless sz == 0, in which case
+ * it's a no-op). It's conceptually close to FreeBSD's strlcpy(), but differs
+ * in what is returned. Given this is internal helper, it's trivial to extend
+ * this, when necessary. Use this instead of strncpy inside libbpf source code.
+ */
+static inline void libbpf_strlcpy(char *dst, const char *src, size_t sz)
+{
+ size_t i;
+
+ if (sz == 0)
+ return;
+
+ sz--;
+ for (i = 0; i < sz && src[i]; i++)
+ dst[i] = src[i];
+ dst[i] = '\0';
+}
+
#define __bpf_percpu_val_align __attribute__((__aligned__(8)))
#define BPF_DECLARE_PERCPU(type, name) \
@@ -13,6 +13,7 @@
#include <ftw.h>
#include "cgroup_helpers.h"
+#include "bpf_util.h"
/*
* To avoid relying on the system setup, when setup_cgroup_env is called
@@ -77,7 +78,7 @@ static int __enable_controllers(const char *cgroup_path, const char *controllers
enable[len] = 0;
close(fd);
} else {
- strncpy(enable, controllers, sizeof(enable));
+ libbpf_strlcpy(enable, controllers, sizeof(enable));
}
snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
@@ -33,6 +33,7 @@
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
#include "xsk.h"
+#include "bpf_util.h"
#ifndef SOL_XDP
#define SOL_XDP 283
@@ -521,25 +522,6 @@ static int xsk_create_bpf_link(struct xsk_socket *xsk)
return 0;
}
-/* Copy up to sz - 1 bytes from zero-terminated src string and ensure that dst
- * is zero-terminated string no matter what (unless sz == 0, in which case
- * it's a no-op). It's conceptually close to FreeBSD's strlcpy(), but differs
- * in what is returned. Given this is internal helper, it's trivial to extend
- * this, when necessary. Use this instead of strncpy inside libbpf source code.
- */
-static inline void libbpf_strlcpy(char *dst, const char *src, size_t sz)
-{
- size_t i;
-
- if (sz == 0)
- return;
-
- sz--;
- for (i = 0; i < sz && src[i]; i++)
- dst[i] = src[i];
- dst[i] = '\0';
-}
-
static int xsk_get_max_queues(struct xsk_socket *xsk)
{
struct ethtool_channels channels = { .cmd = ETHTOOL_GCHANNELS };