On 04/10/2019 02:37 AM, Yonghong Song wrote: > The issue is reported at https://github.com/libbpf/libbpf/issues/28. > > Basically, per C standard, for > void *memcpy(void *dest, const void *src, size_t n) > if "dest" or "src" is NULL, regardless of whether "n" is 0 or not, > the result of memcpy is undefined. clang ubsan reported three such > instances in bpf.c with the following pattern: > memcpy(dest, 0, 0). > > Although in practice, no known compiler will cause issues when > copy size is 0. Let us still fix the issue to silence ubsan > warnings. > > Signed-off-by: Yonghong Song <yhs@xxxxxx> Applied, thanks. I fixed up $SUBJECT while applying to add a subsystem prefix. > --- > tools/lib/bpf/bpf.c | 19 +++++++++---------- > 1 file changed, 9 insertions(+), 10 deletions(-) > > diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c > index a1db869a6fda..78f2400dd2d1 100644 > --- a/tools/lib/bpf/bpf.c > +++ b/tools/lib/bpf/bpf.c > @@ -79,7 +79,6 @@ static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size) > > int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr) > { > - __u32 name_len = create_attr->name ? strlen(create_attr->name) : 0; > union bpf_attr attr; > > memset(&attr, '\0', sizeof(attr)); > @@ -89,8 +88,9 @@ int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr) > attr.value_size = create_attr->value_size; > attr.max_entries = create_attr->max_entries; > attr.map_flags = create_attr->map_flags; > - memcpy(attr.map_name, create_attr->name, > - min(name_len, BPF_OBJ_NAME_LEN - 1)); > + if (create_attr->name) > + memcpy(attr.map_name, create_attr->name, > + min(strlen(create_attr->name), BPF_OBJ_NAME_LEN - 1)); Any reason we don't simplify this to use strncpy() for all these occurrences? Thanks, Daniel
