| Message ID | 20210719085134.43325-2-lmb@cloudflare.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | BPF |
| Headers | show |
| Series | bpf: fix OOB read when printing XDP link fdinfo | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for bpf |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | warning | 4 maintainers not CCed: songliubraving@fb.com yhs@fb.com kafai@fb.com kpsingh@kernel.org |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 11802 this patch: 11802 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 5 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 11304 this patch: 11304 |
| netdev/header_inline | success | Link |
Lorenz Bauer wrote: > We got the following UBSAN report on one of our testing machines: > > ================================================================================ > UBSAN: array-index-out-of-bounds in kernel/bpf/syscall.c:2389:24 > index 6 is out of range for type 'char *[6]' > CPU: 43 PID: 930921 Comm: systemd-coredum Tainted: G O 5.10.48-cloudflare-kasan-2021.7.0 #1 > Hardware name: <snip> > Call Trace: > dump_stack+0x7d/0xa3 > ubsan_epilogue+0x5/0x40 > __ubsan_handle_out_of_bounds.cold+0x43/0x48 > ? seq_printf+0x17d/0x250 > bpf_link_show_fdinfo+0x329/0x380 > ? bpf_map_value_size+0xe0/0xe0 > ? put_files_struct+0x20/0x2d0 > ? __kasan_kmalloc.constprop.0+0xc2/0xd0 > seq_show+0x3f7/0x540 > seq_read_iter+0x3f8/0x1040 > seq_read+0x329/0x500 > ? seq_read_iter+0x1040/0x1040 > ? __fsnotify_parent+0x80/0x820 > ? __fsnotify_update_child_dentry_flags+0x380/0x380 > vfs_read+0x123/0x460 > ksys_read+0xed/0x1c0 > ? __x64_sys_pwrite64+0x1f0/0x1f0 > do_syscall_64+0x33/0x40 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > <snip> > ================================================================================ > ================================================================================ > UBSAN: object-size-mismatch in kernel/bpf/syscall.c:2384:2 > > From the report, we can infer that some array access in bpf_link_show_fdinfo at index 6 > is out of bounds. The obvious candidate is bpf_link_type_strs[BPF_LINK_TYPE_XDP] with > BPF_LINK_TYPE_XDP == 6. It turns out that BPF_LINK_TYPE_XDP is missing from bpf_types.h > and therefore doesn't have an entry in bpf_link_type_strs: > > pos: 0 > flags: 02000000 > mnt_id: 13 > link_type: (null) > link_id: 4 > prog_tag: bcf7977d3b93787c > prog_id: 4 > ifindex: 1 > > Fixes: aa8d3a716b59 ("bpf, xdp: Add bpf_link-based XDP attachment API") > Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> > --- > include/linux/bpf_types.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h > index a9db1eae6796..ae3ac3a2018c 100644 > --- a/include/linux/bpf_types.h > +++ b/include/linux/bpf_types.h > @@ -134,4 +134,5 @@ BPF_LINK_TYPE(BPF_LINK_TYPE_CGROUP, cgroup) > BPF_LINK_TYPE(BPF_LINK_TYPE_ITER, iter) > #ifdef CONFIG_NET > BPF_LINK_TYPE(BPF_LINK_TYPE_NETNS, netns) > +BPF_LINK_TYPE(BPF_LINK_TYPE_XDP, xdp) > #endif > -- > 2.30.2 > Still lgtm. Acked-by; John Fastabend <john.fastabend@gmail.com>
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h index a9db1eae6796..ae3ac3a2018c 100644 --- a/include/linux/bpf_types.h +++ b/include/linux/bpf_types.h @@ -134,4 +134,5 @@ BPF_LINK_TYPE(BPF_LINK_TYPE_CGROUP, cgroup) BPF_LINK_TYPE(BPF_LINK_TYPE_ITER, iter) #ifdef CONFIG_NET BPF_LINK_TYPE(BPF_LINK_TYPE_NETNS, netns) +BPF_LINK_TYPE(BPF_LINK_TYPE_XDP, xdp) #endif
We got the following UBSAN report on one of our testing machines: ================================================================================ UBSAN: array-index-out-of-bounds in kernel/bpf/syscall.c:2389:24 index 6 is out of range for type 'char *[6]' CPU: 43 PID: 930921 Comm: systemd-coredum Tainted: G O 5.10.48-cloudflare-kasan-2021.7.0 #1 Hardware name: <snip> Call Trace: dump_stack+0x7d/0xa3 ubsan_epilogue+0x5/0x40 __ubsan_handle_out_of_bounds.cold+0x43/0x48 ? seq_printf+0x17d/0x250 bpf_link_show_fdinfo+0x329/0x380 ? bpf_map_value_size+0xe0/0xe0 ? put_files_struct+0x20/0x2d0 ? __kasan_kmalloc.constprop.0+0xc2/0xd0 seq_show+0x3f7/0x540 seq_read_iter+0x3f8/0x1040 seq_read+0x329/0x500 ? seq_read_iter+0x1040/0x1040 ? __fsnotify_parent+0x80/0x820 ? __fsnotify_update_child_dentry_flags+0x380/0x380 vfs_read+0x123/0x460 ksys_read+0xed/0x1c0 ? __x64_sys_pwrite64+0x1f0/0x1f0 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 <snip> ================================================================================ ================================================================================ UBSAN: object-size-mismatch in kernel/bpf/syscall.c:2384:2 From the report, we can infer that some array access in bpf_link_show_fdinfo at index 6 is out of bounds. The obvious candidate is bpf_link_type_strs[BPF_LINK_TYPE_XDP] with BPF_LINK_TYPE_XDP == 6. It turns out that BPF_LINK_TYPE_XDP is missing from bpf_types.h and therefore doesn't have an entry in bpf_link_type_strs: pos: 0 flags: 02000000 mnt_id: 13 link_type: (null) link_id: 4 prog_tag: bcf7977d3b93787c prog_id: 4 ifindex: 1 Fixes: aa8d3a716b59 ("bpf, xdp: Add bpf_link-based XDP attachment API") Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> --- include/linux/bpf_types.h | 1 + 1 file changed, 1 insertion(+)