netdev - Re: [PATCH net-next] net: remove sk_is_ipmr() and sk_is

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Message-ID: <CANn89iL5Mjfs7orwjn+H5P6sqyeAguXkKsAj_svrkMZPNWOrbA@mail.gmail.com>
Date: Mon, 19 Jun 2023 19:31:35 +0200
From: Eric Dumazet <edumazet@...gle.com>
To: Jiri Pirko <jiri@...nulli.us>
Cc: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	syzbot <syzkaller@...glegroups.com>, Breno Leitao <leitao@...ian.org>, 
	Willem de Bruijn <willemb@...gle.com>, David Ahern <dsahern@...nel.org>, 
	Kuniyuki Iwashima <kuniyu@...zon.com>
Subject: Re: [PATCH net-next] net: remove sk_is_ipmr() and sk_is_icmpv6() helpers

On Mon, Jun 19, 2023 at 5:18 PM Jiri Pirko <jiri@...nulli.us> wrote:
>
> Mon, Jun 19, 2023 at 02:43:35PM CEST, edumazet@...gle.com wrote:
> >Blamed commit added these helpers for sake of detecting RAW
> >sockets specific ioctl.
> >
> >syzbot complained about it [1].
> >
> >Issue here is that RAW sockets could pretend there was no need
> >to call ipmr_sk_ioctl()
> >
> >Regardless of inet_sk(sk)->inet_num, we must be prepared
> >for ipmr_ioctl() being called later. This must happen
> >from ipmr_sk_ioctl() context only.
> >
> >We could add a safety check in ipmr_ioctl() at the risk of breaking
> >applications.
> >
> >Instead, remove sk_is_ipmr() and sk_is_icmpv6() because their
> >name would be misleading, once we change their implementation.
>
> Hurts my fingers to write this, but it would be easier to follow the
> patch description and actually undestand what you do with imperative
> mood commanding the codebase, without the "we"nesses. But again,
> nevermind :)

It is not the first time you comment on the style of my changelogs.

I would prefer we spend time elsewhere, we obviously have different
ways of writing in English.

Just my two cents.



>
>
> >
> >[1]
> >BUG: KASAN: stack-out-of-bounds in ipmr_ioctl+0xb12/0xbd0 net/ipv4/ipmr.c:1654
> >Read of size 4 at addr ffffc90003aefae4 by task syz-executor105/5004
> >
> >CPU: 0 PID: 5004 Comm: syz-executor105 Not tainted 6.4.0-rc6-syzkaller-01304-gc08afcdcf952 #0
> >Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
> >Call Trace:
> ><TASK>
> >__dump_stack lib/dump_stack.c:88 [inline]
> >dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
> >print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:351
> >print_report mm/kasan/report.c:462 [inline]
> >kasan_report+0x11c/0x130 mm/kasan/report.c:572
> >ipmr_ioctl+0xb12/0xbd0 net/ipv4/ipmr.c:1654
> >raw_ioctl+0x4e/0x1e0 net/ipv4/raw.c:881
> >sock_ioctl_out net/core/sock.c:4186 [inline]
> >sk_ioctl+0x151/0x440 net/core/sock.c:4214
> >inet_ioctl+0x18c/0x380 net/ipv4/af_inet.c:1001
> >sock_do_ioctl+0xcc/0x230 net/socket.c:1189
> >sock_ioctl+0x1f8/0x680 net/socket.c:1306
> >vfs_ioctl fs/ioctl.c:51 [inline]
> >__do_sys_ioctl fs/ioctl.c:870 [inline]
> >__se_sys_ioctl fs/ioctl.c:856 [inline]
> >__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
> >do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> >do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
> >entry_SYSCALL_64_after_hwframe+0x63/0xcd
> >RIP: 0033:0x7f2944bf6ad9
> >Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
> >RSP: 002b:00007ffd8897a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> >RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2944bf6ad9
> >RDX: 0000000000000000 RSI: 00000000000089e1 RDI: 0000000000000003
> >RBP: 00007f2944bbac80 R08: 0000000000000000 R09: 0000000000000000
> >R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2944bbad10
> >R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> ></TASK>
> >
> >The buggy address belongs to stack of task syz-executor105/5004
> >and is located at offset 36 in frame:
> >sk_ioctl+0x0/0x440 net/core/sock.c:4172
> >
> >This frame has 2 objects:
> >[32, 36) 'karg'
> >[48, 88) 'buffer'
> >
> >Fixes: e1d001fa5b47 ("net: ioctl: Use kernel memory on protocol ioctl callbacks")
> >Reported-by: syzbot <syzkaller@...glegroups.com>
> >Signed-off-by: Eric Dumazet <edumazet@...gle.com>
>
> Reviewed-by: Jiri Pirko <jiri@...dia.com>