linux-kernel - Re: [syzbot] [bpf?] [net?] BUG: unable to handle kernel NULL pointer dereference in sk_psock_verdict_data

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Message-ID: <000000000000fb3b68060a088a68@google.com>
Date:   Mon, 13 Nov 2023 05:21:07 -0800
From:   syzbot <syzbot+fd7b34375c1c8ce29c93@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org, mukattreyee@...il.com,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bpf?] [net?] BUG: unable to handle kernel NULL pointer
 dereference in sk_psock_verdict_data_ready

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: unable to handle kernel NULL pointer dereference in sk_psock_verdict_data_ready

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 1c0b3067 P4D 1c0b3067 PUD 698e0067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 8102 Comm: syz-executor.5 Not tainted 6.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc9000ae77868 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88801e9e6000 RCX: ffffffff88538a6f
RDX: 1ffff11003ba825c RSI: ffffffff88538a79 RDI: ffff88801e9e6000
RBP: 0000000000000004 R08: 0000000000000007 R09: 0000000000000000
R10: ffff88801dd41000 R11: 0000000000000000 R12: ffff88801dd41000
R13: 0000000000000000 R14: ffff88801e9e6000 R15: ffff88801e9e6000
FS:  00007f15c3c206c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000019717000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 sk_psock_verdict_data_ready net/core/skmsg.c:1228 [inline]
 sk_psock_verdict_data_ready+0x207/0x3d0 net/core/skmsg.c:1208
 unix_dgram_sendmsg+0x11b3/0x1ca0 net/unix/af_unix.c:2116
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0xd5/0x180 net/socket.c:745
 ____sys_sendmsg+0x2ac/0x940 net/socket.c:2584
 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2638
 __sys_sendmmsg+0x1a1/0x450 net/socket.c:2724
 __do_sys_sendmmsg net/socket.c:2753 [inline]
 __se_sys_sendmmsg net/socket.c:2750 [inline]
 __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2750
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f15c2e7cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f15c3c200c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f15c2f9bf80 RCX: 00007f15c2e7cae9
RDX: 0000000000000002 RSI: 0000000020001680 RDI: 0000000000000003
RBP: 00007f15c2ec847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f15c2f9bf80 R15: 00007ffe1c491ce8
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc9000ae77868 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88801e9e6000 RCX: ffffffff88538a6f
RDX: 1ffff11003ba825c RSI: ffffffff88538a79 RDI: ffff88801e9e6000
RBP: 0000000000000004 R08: 0000000000000007 R09: 0000000000000000
R10: ffff88801dd41000 R11: 0000000000000000 R12: ffff88801dd41000
R13: 0000000000000000 R14: ffff88801e9e6000 R15: ffff88801e9e6000
FS:  00007f15c3c206c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000019717000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


Tested on:

commit:         b85ea95d Linux 6.7-rc1
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=1573bc8f680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5e0ea92caaa75735
dashboard link: https://syzkaller.appspot.com/bug?extid=fd7b34375c1c8ce29c93
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.