| Message ID | 20220727204808.13210-1-david.faust@oracle.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf-next] libbpf: avoid mmap for size 0 sections | expand |
On Wed, Jul 27, 2022 at 01:48:08PM -0700, David Faust wrote: > When populating maps in bpf_object__init_global_data_maps(), recognized > sections with no data (e.g. a .bss with size 0) lead to an mmap of 0 > bytes which fails with EINVAL. > > Add a check to skip mapping sections which are present, but empty. > > Signed-off-by: David Faust <david.faust@oracle.com> > --- > tools/lib/bpf/libbpf.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index b01fe01b0761..4e7ceb4f5a27 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -1642,6 +1642,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj) > for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) { > sec_desc = &obj->efile.secs[sec_idx]; > > + /* Skip recognized sections with size 0. */ > + if (sec_desc->data && sec_desc->data->d_size == 0) > + continue; nit missing tab indent also we seem to check for size in bpf_object__elf_collect before adding SEC_DATA/SEC_RODATA but not SEC_BSS I think the check should be rather in bpf_object__elf_collect before we add the desc for it jirka > + > switch (sec_desc->sec_type) { > case SEC_DATA: > sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx)); > -- > 2.36.1 >
On 7/28/22 07:15, Jiri Olsa wrote: > On Wed, Jul 27, 2022 at 01:48:08PM -0700, David Faust wrote: >> When populating maps in bpf_object__init_global_data_maps(), recognized >> sections with no data (e.g. a .bss with size 0) lead to an mmap of 0 >> bytes which fails with EINVAL. >> >> Add a check to skip mapping sections which are present, but empty. >> >> Signed-off-by: David Faust <david.faust@oracle.com> >> --- >> tools/lib/bpf/libbpf.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c >> index b01fe01b0761..4e7ceb4f5a27 100644 >> --- a/tools/lib/bpf/libbpf.c >> +++ b/tools/lib/bpf/libbpf.c >> @@ -1642,6 +1642,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj) >> for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) { >> sec_desc = &obj->efile.secs[sec_idx]; >> >> + /* Skip recognized sections with size 0. */ >> + if (sec_desc->data && sec_desc->data->d_size == 0) >> + continue; > > nit missing tab indent > > also we seem to check for size in bpf_object__elf_collect > before adding SEC_DATA/SEC_RODATA but not SEC_BSS > > I think the check should be rather in bpf_object__elf_collect > before we add the desc for it I see, thanks. Will send an updated patch. David > > jirka > >> + >> switch (sec_desc->sec_type) { >> case SEC_DATA: >> sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx)); >> -- >> 2.36.1 >>
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index b01fe01b0761..4e7ceb4f5a27 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -1642,6 +1642,10 @@ static int bpf_object__init_global_data_maps(struct bpf_object *obj) for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) { sec_desc = &obj->efile.secs[sec_idx]; + /* Skip recognized sections with size 0. */ + if (sec_desc->data && sec_desc->data->d_size == 0) + continue; + switch (sec_desc->sec_type) { case SEC_DATA: sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
When populating maps in bpf_object__init_global_data_maps(), recognized sections with no data (e.g. a .bss with size 0) lead to an mmap of 0 bytes which fails with EINVAL. Add a check to skip mapping sections which are present, but empty. Signed-off-by: David Faust <david.faust@oracle.com> --- tools/lib/bpf/libbpf.c | 4 ++++ 1 file changed, 4 insertions(+)