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SubjectRe: [PATCH bpf 1/2] bpf: fix alignment of netns_dev/netns_ino fields in bpf_{map,prog}_info
Hi,

Looks like the ABI bug in bpf_map_info and bpf_prog info introduced
in 4.16 is going to slip into 4.17, causing extra pain to 32-bit
userspace. I'm adding Linus to this thread in hope it might help
to get a fix applied before 4.17 is released.

On Wed, May 30, 2018 at 09:18:58PM +0300, Dmitry V. Levin wrote:
> On Sun, May 27, 2018 at 01:28:42PM +0200, Eugene Syromiatnikov wrote:
> > Recent introduction of netns_dev/netns_ino to bpf_map_info/bpf_prog info
> > has broken compat, as offsets of these fields are different in 32-bit
> > and 64-bit ABIs. One fix (other than implementing compat support in
> > syscall in order to handle this discrepancy) is to use __aligned_u64
> > instead of __u64 for these fields.
> >
> > Reported-by: Dmitry V. Levin <ldv@altlinux.org>
> > Fixes: 52775b33bb507 ("bpf: offload: report device information about
> > offloaded maps")
> > Fixes: 675fc275a3a2d ("bpf: offload: report device information for
> > offloaded programs")
> >
> > Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
>
> Reviewed-by: "Dmitry V. Levin" <ldv@altlinux.org>
> Cc: <stable@vger.kernel.org> # v4.16+
>
> Thanks,
>
> > ---
> > include/uapi/linux/bpf.h | 8 ++++----
> > tools/include/uapi/linux/bpf.h | 8 ++++----
> > 2 files changed, 8 insertions(+), 8 deletions(-)
> >
> > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > index c5ec897..903010a 100644
> > --- a/include/uapi/linux/bpf.h
> > +++ b/include/uapi/linux/bpf.h
> > @@ -1017,8 +1017,8 @@ struct bpf_prog_info {
> > __aligned_u64 map_ids;
> > char name[BPF_OBJ_NAME_LEN];
> > __u32 ifindex;
> > - __u64 netns_dev;
> > - __u64 netns_ino;
> > + __aligned_u64 netns_dev;
> > + __aligned_u64 netns_ino;
> > } __attribute__((aligned(8)));
> >
> > struct bpf_map_info {
> > @@ -1030,8 +1030,8 @@ struct bpf_map_info {
> > __u32 map_flags;
> > char name[BPF_OBJ_NAME_LEN];
> > __u32 ifindex;
> > - __u64 netns_dev;
> > - __u64 netns_ino;
> > + __aligned_u64 netns_dev;
> > + __aligned_u64 netns_ino;
> > } __attribute__((aligned(8)));
> >
> > /* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
> > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> > index c5ec897..903010a 100644
> > --- a/tools/include/uapi/linux/bpf.h
> > +++ b/tools/include/uapi/linux/bpf.h
> > @@ -1017,8 +1017,8 @@ struct bpf_prog_info {
> > __aligned_u64 map_ids;
> > char name[BPF_OBJ_NAME_LEN];
> > __u32 ifindex;
> > - __u64 netns_dev;
> > - __u64 netns_ino;
> > + __aligned_u64 netns_dev;
> > + __aligned_u64 netns_ino;
> > } __attribute__((aligned(8)));
> >
> > struct bpf_map_info {
> > @@ -1030,8 +1030,8 @@ struct bpf_map_info {
> > __u32 map_flags;
> > char name[BPF_OBJ_NAME_LEN];
> > __u32 ifindex;
> > - __u64 netns_dev;
> > - __u64 netns_ino;
> > + __aligned_u64 netns_dev;
> > + __aligned_u64 netns_ino;
> > } __attribute__((aligned(8)));
> >
> > /* User bpf_sock_addr struct to access socket fields and sockaddr struct passed


--
ldv
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