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Message-ID: <tencent_B91CA31B889B06CF4292592F97892A53AF08@qq.com>
Date: Wed, 2 Nov 2022 20:59:10 +0800
From: Rong Tao <rtoax@...mail.com>
To: daniel@...earbox.net
Cc: andrii.nakryiko@...il.com, andrii@...nel.org, ast@...nel.org,
bpf@...r.kernel.org, david.laight@...lab.com, haoluo@...gle.com,
john.fastabend@...il.com, jolsa@...nel.org, kpsingh@...nel.org,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
martin.lau@...ux.dev, mykolal@...com, rongtao@...tc.cn,
rtoax@...mail.com, sdf@...gle.com, shuah@...nel.org,
song@...nel.org, yhs@...com
Subject: [PATCH bpf-next] selftests/bpf: cgroup_helpers.c: Fix strncpy() fortify warning
From: Rong Tao <rongtao@...tc.cn>
Move libbpf_strlcpy() to libbpf_common.h, and replace strncpy() with
libbpf_strlcpy(), fix compile warning.
We can't use libbpf_internal.h directly, because it introduces a lot of
header dependency issues. So move libbpf_strlcpy() into libbpf_common.h,
and if you need to use the libbpf_strlcpy() function, you need to include
the header file libbpf.h
How to reproduce this compilation warning:
$ make -C samples/bpf
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@...tc.cn>
---
tools/lib/bpf/libbpf_common.h | 19 +++++++++++++++++++
tools/lib/bpf/libbpf_internal.h | 19 -------------------
tools/testing/selftests/bpf/cgroup_helpers.c | 3 ++-
tools/testing/selftests/bpf/xsk.c | 19 -------------------
4 files changed, 21 insertions(+), 39 deletions(-)
diff --git a/tools/lib/bpf/libbpf_common.h b/tools/lib/bpf/libbpf_common.h
index 9a7937f339df..9d5132e0bec9 100644
--- a/tools/lib/bpf/libbpf_common.h
+++ b/tools/lib/bpf/libbpf_common.h
@@ -70,4 +70,23 @@
}; \
})
+/* 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';
+}
+
#endif /* __LIBBPF_LIBBPF_COMMON_H */
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 377642ff51fc..902110ffb7a6 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -191,25 +191,6 @@ static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size)
return realloc(ptr, total);
}
-/* 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';
-}
-
__u32 get_kernel_version(void);
struct btf;
diff --git a/tools/testing/selftests/bpf/cgroup_helpers.c b/tools/testing/selftests/bpf/cgroup_helpers.c
index e914cc45b766..e3bfe2b13018 100644
--- a/tools/testing/selftests/bpf/cgroup_helpers.c
+++ b/tools/testing/selftests/bpf/cgroup_helpers.c
@@ -11,6 +11,7 @@
#include <fcntl.h>
#include <unistd.h>
#include <ftw.h>
+#include <bpf/libbpf.h>
#include "cgroup_helpers.h"
@@ -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);
diff --git a/tools/testing/selftests/bpf/xsk.c b/tools/testing/selftests/bpf/xsk.c
index 0b3ff49c740d..4b6890e2a0a9 100644
--- a/tools/testing/selftests/bpf/xsk.c
+++ b/tools/testing/selftests/bpf/xsk.c
@@ -521,25 +521,6 @@ 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 };
--
2.31.1
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