[syzbot] general protection fault in pse_prepare_data

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 55be6084c8e0 Merge tag 'timers-core-2022-10-05' of git://g..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=140d5a2c880000
kernel config: https://syzkaller.appspot.com/x/.config?x=df75278aabf0681a
dashboard link: https://syzkaller.appspot.com/bug?extid=81c4b4bbba6eea2cfcae
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13470244880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=146e88b4880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9d967e5d91fa/disk-55be6084.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9a8cffcbc089/vmlinux-55be6084.xz

Bisection is inconclusive: the first bad commit could be any of:

331834898f2b Merge branch 'add-generic-pse-support'
66741b4e94ca net: pse-pd: add regulator based PSE driver
2a4187f4406e once: rename _SLOW to _SLEEPABLE
f05dfdaf567a dt-bindings: net: pse-dt: add bindings for regulator based PoDL PSE controller
18ff0bcda6d1 ethtool: add interface to interact with Ethernet Power Equipment
e52f7c1ddf3e Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
681bf011b9b5 eth: pse: add missing static inlines

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11fc42b4880000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+81c4b4...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
CPU: 1 PID: 3609 Comm: syz-executor227 Not tainted 6.0.0-syzkaller-09589-g55be6084c8e0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
RIP: 0010:pse_prepare_data+0x66/0x1e0 net/ethtool/pse-pd.c:67
Code: 89 c6 e8 dd f4 e0 f9 45 85 e4 0f 88 b3 00 00 00 e8 0f f8 e0 f9 48 8d 7d 40 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 36 01 00 00 49 8d bd 98 0b 00 00 4c 8b 65 40 48
RSP: 0018:ffffc90003cff398 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888020324600 RCX: 0000000000000000
RDX: 0000000000000008 RSI: ffffffff879a5231 RDI: 0000000000000040
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8880788f2000 R14: ffff8880712e0598 R15: ffffffff879a51e0
FS: 000055555594f300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 0000000025df8000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ethnl_default_dump_one net/ethtool/netlink.c:442 [inline]
ethnl_default_dumpit+0x4a4/0xe80 net/ethtool/netlink.c:494
netlink_dump+0x541/0xc20 net/netlink/af_netlink.c:2275
__netlink_dump_start+0x647/0x900 net/netlink/af_netlink.c:2380
genl_family_rcv_msg_dumpit+0x1c9/0x310 net/netlink/genetlink.c:689
genl_family_rcv_msg net/netlink/genetlink.c:805 [inline]
genl_rcv_msg+0x55d/0x780 net/netlink/genetlink.c:825
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2540
genl_rcv+0x24/0x40 net/netlink/genetlink.c:836
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
____sys_sendmsg+0x712/0x8c0 net/socket.c:2482
___sys_sendmsg+0x110/0x1b0 net/socket.c:2536
__sys_sendmsg+0xf3/0x1c0 net/socket.c:2565
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f626f3dd579
Code: 28 c3 e8 4a 15 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:00007ffddc5fcbc8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffddc5fcbd8 RCX: 00007f626f3dd579
RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffddc5fcbe0
R13: 00007ffddc5fcc00 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:pse_prepare_data+0x66/0x1e0 net/ethtool/pse-pd.c:67
Code: 89 c6 e8 dd f4 e0 f9 45 85 e4 0f 88 b3 00 00 00 e8 0f f8 e0 f9 48 8d 7d 40 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 36 01 00 00 49 8d bd 98 0b 00 00 4c 8b 65 40 48
RSP: 0018:ffffc90003cff398 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888020324600 RCX: 0000000000000000
RDX: 0000000000000008 RSI: ffffffff879a5231 RDI: 0000000000000040
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8880788f2000 R14: ffff8880712e0598 R15: ffffffff879a51e0
FS: 000055555594f300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 0000000025df8000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 89 c6 mov %eax,%esi
2: e8 dd f4 e0 f9 callq 0xf9e0f4e4
7: 45 85 e4 test %r12d,%r12d
a: 0f 88 b3 00 00 00 js 0xc3
10: e8 0f f8 e0 f9 callq 0xf9e0f824
15: 48 8d 7d 40 lea 0x40(%rbp),%rdi
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 48 89 fa mov %rdi,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 36 01 00 00 jne 0x16a
34: 49 8d bd 98 0b 00 00 lea 0xb98(%r13),%rdi
3b: 4c 8b 65 40 mov 0x40(%rbp),%r12
3f: 48 rex.W


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

[Jakub Kicinski]

Yeah, looking at ethtool internals - info can be NULL :(

For reasons I haven't quite grasped yet myself we use a different
structure for info on do and dump which makes getting to extack in
generic code inconvenient.

[Xin Long]

It seems that eeprom_prepare_data() doesn't check info before
accessing info->extack either.

[Jakub Kicinski]

On Wed, 19 Oct 2022 22:25:47 -0400 Xin Long wrote:
> > Yeah, looking at ethtool internals - info can be NULL :(
> It seems that eeprom_prepare_data() doesn't check info before
> accessing info->extack either.

Good catch, looks like that one dumps as well!

Perhaps we should require netdevsim support for all new commands
going forward :S Otherwise this code is hard for syzbot to exercise.