netdev - Re: [PATCH bpf-next] bpf: fix btf_task_struct_ids w/o CONFIG_DEBUG_INFO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CANn89iLULCxZ+p-zkZVTLObLvJ+z34nEqS-e3nmA8MK0cKzi=g@mail.gmail.com>
Date:   Tue, 9 Nov 2021 14:38:52 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Song Liu <songliubraving@...com>
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org, ast@...nel.org,
        daniel@...earbox.net, andrii@...nel.org, Kernel-team@...com
Subject: Re: [PATCH bpf-next] bpf: fix btf_task_struct_ids w/o CONFIG_DEBUG_INFO_BTF

On Tue, Nov 9, 2021 at 2:25 PM Song Liu <songliubraving@...com> wrote:
>
> This fixes KASAN oops like
>
> BUG: KASAN: global-out-of-bounds in task_iter_init+0x212/0x2e7 kernel/bpf/task_iter.c:661
> Read of size 4 at addr ffffffff90297404 by task swapper/0/1
>
> CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.15.0-syzkaller #0
> Hardware name: ... Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
> print_address_description.constprop.0.cold+0xf/0x309 mm/kasan/report.c:256
> __kasan_report mm/kasan/report.c:442 [inline]
> kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
> task_iter_init+0x212/0x2e7 kernel/bpf/task_iter.c:661
> do_one_initcall+0x103/0x650 init/main.c:1295
> do_initcall_level init/main.c:1368 [inline]
> do_initcalls init/main.c:1384 [inline]
> do_basic_setup init/main.c:1403 [inline]
> kernel_init_freeable+0x6b1/0x73a init/main.c:1606
> kernel_init+0x1a/0x1d0 init/main.c:1497
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> </TASK>
>

Please add a Fixes: tag

Also you can add

Reported-by: syzbot+e0d81ec552a21d9071aa@...kaller.appspotmail.com


> Reported-by: Eric Dumazet <edumazet@...gle.com>
> Signed-off-by: Song Liu <songliubraving@...com>
> ---
>  kernel/bpf/btf.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index cdb0fba656006..6db929a5826d4 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -6342,10 +6342,14 @@ const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
>         .arg4_type      = ARG_ANYTHING,
>  };
>
> +#ifdef CONFIG_DEBUG_INFO_BTF
>  BTF_ID_LIST_GLOBAL(btf_task_struct_ids)
>  BTF_ID(struct, task_struct)
>  BTF_ID(struct, file)
>  BTF_ID(struct, vm_area_struct)
> +#else
> +u32 btf_task_struct_ids[3];
> +#endif

What about adding to  BTF_ID_LIST_GLOBAL() another argument ?

BTF_ID_LIST_GLOBAL(btf_task_struct_ids, 3)

This would avoid this #ifdef

I understand commit 079ef53673f2e3b3ee1728800311f20f28eed4f7
hardcoded a [5] value, maybe we can do slightly better with exact
boundary checks for KASAN.

>
>  /* BTF ID set registration API for modules */
>
> --
> 2.30.2
>