linux-kernel - Re: general protection fault in raw_seq

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Message-ID: <CAL+tcoBTYoExVcmBUfphj3k3RN9LgMRUcSgALfWonFv_SkC=+A@mail.gmail.com>
Date:   Fri, 31 Mar 2023 13:31:01 +0800
From:   Jason Xing <kerneljasonxing@...il.com>
To:     Kuniyuki Iwashima <kuniyu@...zon.com>
Cc:     threeearcat@...il.com, davem@...emloft.net, dsahern@...nel.org,
        edumazet@...gle.com, kuba@...nel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, pabeni@...hat.com
Subject: Re: general protection fault in raw_seq_start

On Fri, Mar 31, 2023 at 6:08 AM Kuniyuki Iwashima <kuniyu@...zon.com> wrote:
>
> From:   "Dae R. Jeong" <threeearcat@...il.com>
> Date:   Sun, 26 Mar 2023 21:12:08 +0900
> > Hi,
> >
> > We observed an issue "general protection fault in raw_seq_start"
> > during fuzzing.
> >
> > Unfortunately, we have not found a reproducer for the crash yet. We
> > will inform you if we have any update on this crash.
> > Detailed crash information is attached below.
> >
> > Best regards,
> > Dae R. Jeong
> >
> > -----
> >
> > - Kernel version
> >   6.2
> >
> > - Last executed input
> >   unshare(0x40060200)
> >   r0 = syz_open_procfs(0x0, &(0x7f0000002080)='net/raw\x00')
> >   socket$inet_icmp_raw(0x2, 0x3, 0x1)
> >   ppoll(0x0, 0x0, 0x0, 0x0, 0x0)
> >   socket$inet_icmp_raw(0x2, 0x3, 0x1)
> >   pread64(r0, &(0x7f0000000000)=""/10, 0xa, 0x10000000007f)
>
> Thanks for reporting the issue.
>
> It seems we need to use RCU variant in raw_get_first().
> I'll post a patch.
>
> ---
> diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
> index 3cf68695b40d..fe0d1ad20b35 100644
> --- a/net/ipv4/raw.c
> +++ b/net/ipv4/raw.c
> @@ -957,7 +957,7 @@ static struct sock *raw_get_first(struct seq_file *seq, int bucket)
>         for (state->bucket = bucket; state->bucket < RAW_HTABLE_SIZE;
>                         ++state->bucket) {
>                 hlist = &h->ht[state->bucket];
> -               sk_nulls_for_each(sk, hnode, hlist) {
> +               sk_nulls_for_each_rcu(sk, hnode, hlist) {

Hello Kuniyuki,

I'm wondering if we should also use rcu_read_lock()/_unlock() pair to protect?

CC: Eric

It seems that we have to convert all the sk_nulls_for_each() to
sk_nulls_for_each_rcu() with the rcu_read_lock/_unlock protection in
net/ipv4/raw.c?

Thanks,
Jason

>                         if (sock_net(sk) == seq_file_net(seq))
>                                 return sk;
>                 }
> ---
>
> Thanks,
> Kuniyuki
>
>
>
> >
> > - Crash report
> > general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN
> > KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
> > CPU: 2 PID: 20952 Comm: syz-executor.0 Not tainted 6.2.0-g048ec869bafd-dirty #7
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
> > RIP: 0010:read_pnet include/net/net_namespace.h:383 [inline]
> > RIP: 0010:sock_net include/net/sock.h:649 [inline]
> > RIP: 0010:raw_get_next net/ipv4/raw.c:974 [inline]
> > RIP: 0010:raw_get_idx net/ipv4/raw.c:986 [inline]
> > RIP: 0010:raw_seq_start+0x431/0x800 net/ipv4/raw.c:995
> > Code: ef e8 33 3d 94 f7 49 8b 6d 00 4c 89 ef e8 b7 65 5f f7 49 89 ed 49 83 c5 98 0f 84 9a 00 00 00 48 83 c5 c8 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 ef e8 00 3d 94 f7 4c 8b 7d 00 48 89 ef
> > RSP: 0018:ffffc9001154f9b0 EFLAGS: 00010206
> > RAX: 0000000000000005 RBX: 1ffff1100302c8fd RCX: 0000000000000000
> > RDX: 0000000000000028 RSI: ffffc9001154f988 RDI: ffffc9000f77a338
> > RBP: 0000000000000029 R08: ffffffff8a50ffb4 R09: fffffbfff24b6bd9
> > R10: fffffbfff24b6bd9 R11: 0000000000000000 R12: ffff88801db73b78
> > R13: fffffffffffffff9 R14: dffffc0000000000 R15: 0000000000000030
> > FS:  00007f843ae8e700(0000) GS:ffff888063700000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 000055bb9614b35f CR3: 000000003c672000 CR4: 00000000003506e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> >  <TASK>
> >  seq_read_iter+0x4c6/0x10f0 fs/seq_file.c:225
> >  seq_read+0x224/0x320 fs/seq_file.c:162
> >  pde_read fs/proc/inode.c:316 [inline]
> >  proc_reg_read+0x23f/0x330 fs/proc/inode.c:328
> >  vfs_read+0x31e/0xd30 fs/read_write.c:468
> >  ksys_pread64 fs/read_write.c:665 [inline]
> >  __do_sys_pread64 fs/read_write.c:675 [inline]
> >  __se_sys_pread64 fs/read_write.c:672 [inline]
> >  __x64_sys_pread64+0x1e9/0x280 fs/read_write.c:672
> >  do_syscall_x64 arch/x86/entry/common.c:51 [inline]
> >  do_syscall_64+0x4e/0xa0 arch/x86/entry/common.c:82
> >  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> > RIP: 0033:0x478d29
> > Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 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 bc ff ff ff f7 d8 64 89 01 48
> > RSP: 002b:00007f843ae8dbe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000011
> > RAX: ffffffffffffffda RBX: 0000000000791408 RCX: 0000000000478d29
> > RDX: 000000000000000a RSI: 0000000020000000 RDI: 0000000000000003
> > RBP: 00000000f477909a R08: 0000000000000000 R09: 0000000000000000
> > R10: 000010000000007f R11: 0000000000000246 R12: 0000000000791740
> > R13: 0000000000791414 R14: 0000000000791408 R15: 00007ffc2eb48a50
> >  </TASK>
> > Modules linked in:
> > ---[ end trace 0000000000000000 ]---
> > RIP: 0010:read_pnet include/net/net_namespace.h:383 [inline]
> > RIP: 0010:sock_net include/net/sock.h:649 [inline]
> > RIP: 0010:raw_get_next net/ipv4/raw.c:974 [inline]
> > RIP: 0010:raw_get_idx net/ipv4/raw.c:986 [inline]
> > RIP: 0010:raw_seq_start+0x431/0x800 net/ipv4/raw.c:995
> > Code: ef e8 33 3d 94 f7 49 8b 6d 00 4c 89 ef e8 b7 65 5f f7 49 89 ed 49 83 c5 98 0f 84 9a 00 00 00 48 83 c5 c8 48 89 e8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 ef e8 00 3d 94 f7 4c 8b 7d 00 48 89 ef
> > RSP: 0018:ffffc9001154f9b0 EFLAGS: 00010206
> > RAX: 0000000000000005 RBX: 1ffff1100302c8fd RCX: 0000000000000000
> > RDX: 0000000000000028 RSI: ffffc9001154f988 RDI: ffffc9000f77a338
> > RBP: 0000000000000029 R08: ffffffff8a50ffb4 R09: fffffbfff24b6bd9
> > R10: fffffbfff24b6bd9 R11: 0000000000000000 R12: ffff88801db73b78
> > R13: fffffffffffffff9 R14: dffffc0000000000 R15: 0000000000000030
> > FS:  00007f843ae8e700(0000) GS:ffff888063700000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007f92ff166000 CR3: 000000003c672000 CR4: 00000000003506e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400