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| author | Andrii Nakryiko <andrii@kernel.org> | 2021-12-10 16:40:43 -0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-12-14 15:47:56 +0100 |
| commit | 9fc205b413b3f3e9502fa92151fba63b91230454 (patch) | |
| tree | 9964b204c6a1721168b7041e060df59b5123ce7a /tools/lib/bpf/libbpf.c | |
| parent | 4581e676d3be9d8c921a48bf18e92c5a8f31bf13 (diff) | |
| download | lwn-9fc205b413b3f3e9502fa92151fba63b91230454.tar.gz lwn-9fc205b413b3f3e9502fa92151fba63b91230454.zip | |
libbpf: Add sane strncpy alternative and use it internally
strncpy() has a notoriously error-prone semantics which makes GCC
complain about it a lot (and quite often completely completely falsely
at that). Instead of pleasing GCC all the time (-Wno-stringop-truncation
is unfortunately only supported by GCC, so it's a bit too messy to just
enable it in Makefile), add libbpf-internal libbpf_strlcpy() helper
which follows what FreeBSD's strlcpy() does and what most people would
expect from strncpy(): copies up to N-1 first bytes from source string
into destination string and ensures zero-termination afterwards.
Replace all the relevant uses of strncpy/strncat/memcpy in libbpf with
libbpf_strlcpy().
This also fixes the issue reported by Emmanuel Deloget in xsk.c where
memcpy() could access source string beyond its end.
Fixes: 2f6324a3937f8 (libbpf: Support shared umems between queues and devices)
Reported-by: Emmanuel Deloget <emmanuel.deloget@eho.link>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211211004043.2374068-1-andrii@kernel.org
Diffstat (limited to 'tools/lib/bpf/libbpf.c')
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 902f1ad5b7e6..c6d84b01a59e 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -1201,12 +1201,10 @@ static struct bpf_object *bpf_object__new(const char *path, strcpy(obj->path, path); if (obj_name) { - strncpy(obj->name, obj_name, sizeof(obj->name) - 1); - obj->name[sizeof(obj->name) - 1] = 0; + libbpf_strlcpy(obj->name, obj_name, sizeof(obj->name)); } else { /* Using basename() GNU version which doesn't modify arg. */ - strncpy(obj->name, basename((void *)path), - sizeof(obj->name) - 1); + libbpf_strlcpy(obj->name, basename((void *)path), sizeof(obj->name)); end = strchr(obj->name, '.'); if (end) *end = 0; @@ -1358,7 +1356,7 @@ static int bpf_object__check_endianness(struct bpf_object *obj) static int bpf_object__init_license(struct bpf_object *obj, void *data, size_t size) { - memcpy(obj->license, data, min(size, sizeof(obj->license) - 1)); + libbpf_strlcpy(obj->license, data, sizeof(obj->license)); pr_debug("license of %s is %s\n", obj->path, obj->license); return 0; } |