Date:   Fri, 16 Sep 2022 00:02:22 +0800
From:   Rondreis <linhaoguo86@...il.com>
To:     pabeni@...hat.com, huangguangbin2@...wei.com,
        john.fastabend@...il.com, hawk@...nel.org, trix@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: general protection fault in ethtool_get_drvinfo

Hello,

When fuzzing the Linux kernel driver v6.0-rc4, the following crash was
triggered.

HEAD commit: 7e18e42e4b280c85b76967a9106a13ca61c16179
git tree: upstream

kernel config: https://pastebin.com/raw/xtrgsXP3
C reproducer: https://pastebin.com/raw/RtX3naYU
console output: https://pastebin.com/raw/HqjSMu2n

Basically, in the c reproducer, we use the gadget module to emulate
attaching a USB device(vendor id: 0x1b3d, product id: 0x19c, with the
midi function) and executing some simple sequence of system calls.
To reproduce this crash, we utilize a third-party library to emulate
the attaching process: https://github.com/linux-usb-gadgets/libusbgx.
Just clone this repository, install it, and compile the c
reproducer with ``` gcc crash.c -lusbgx -lconfig -o crash ``` will do
the trick.

I would appreciate it if you have any idea how to solve this bug.

The crash report is as follows:
general protection fault, probably for non-canonical address
0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 6495 Comm: systemd-udevd Not tainted 6.0.0-rc4+ #20
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:ethtool_get_drvinfo+0x533/0x7d0 net/ethtool/ioctl.c:723
Code: 49 8d 7d 68 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 60 02 00 00
48 b8 00 00 00 00 00 fc ff df 4d 8b 6d 68 4c 89 ea 48 c1 ea 03 <80> 3c
02 00 0f 85 34 02 00 00 4d 8b 7d 00 4c 8d 73 0c 41 bd 1f 00
RSP: 0018:ffffc9000215f8c0 EFLAGS: 00010256
RAX: dffffc0000000000 RBX: ffff88804af0e000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff888013aa45a8 RDI: ffff8880152d0cf8
RBP: ffff8880225ba000 R08: ffffffff877f1966 R09: ffffed10095e1c0f
R10: ffff88804af0e073 R11: ffffed10095e1c0e R12: ffffffff8ad292a0
R13: 0000000000000000 R14: ffff8880225ba658 R15: ffff88804af0e06c
FS: 00007f60d186e6c0(0000) GS:ffff88807ec00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb0b563b000 CR3: 0000000046f26000 CR4: 0000000000350ee0
Call Trace:
<TASK>
__dev_ethtool net/ethtool/ioctl.c:2800 [inline]
dev_ethtool+0x18df/0x54f0 net/ethtool/ioctl.c:3038
dev_ioctl+0x510/0xe50 net/core/dev_ioctl.c:524
sock_do_ioctl+0x1c0/0x250 net/socket.c:1183
sock_ioctl+0x3b3/0x680 net/socket.c:1286
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+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f60d152fcc7
Code: 00 00 00 48 8b 05 c9 91 0c 00 64 c7 00 26 00 00 00 48 c7 c0 ff
ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 8b 0d 99 91 0c 00 f7 d8 64 89 01 48
RSP: 002b:00007ffc43cbe4d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00005634ecc852c0 RCX: 00007f60d152fcc7
RDX: 00007ffc43cbe5a0 RSI: 0000000000008946 RDI: 0000000000000006
RBP: 00007ffc43cbe5d0 R08: 00005634eccc7bc0 R09: 0000000000000000
R10: 00007f60d186e4c0 R11: 0000000000000246 R12: 00005634eccc7bc0
R13: 00005634ecccfb70 R14: 00007ffc43cbe5a0 R15: 0000000000000007
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ethtool_get_drvinfo+0x533/0x7d0 net/ethtool/ioctl.c:723
Code: 49 8d 7d 68 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 60 02 00 00
48 b8 00 00 00 00 00 fc ff df 4d 8b 6d 68 4c 89 ea 48 c1 ea 03 <80> 3c
02 00 0f 85 34 02 00 00 4d 8b 7d 00 4c 8d 73 0c 41 bd 1f 00
RSP: 0018:ffffc9000215f8c0 EFLAGS: 00010256
RAX: dffffc0000000000 RBX: ffff88804af0e000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff888013aa45a8 RDI: ffff8880152d0cf8
RBP: ffff8880225ba000 R08: ffffffff877f1966 R09: ffffed10095e1c0f
R10: ffff88804af0e073 R11: ffffed10095e1c0e R12: ffffffff8ad292a0
R13: 0000000000000000 R14: ffff8880225ba658 R15: ffff88804af0e06c
FS: 00007f60d186e6c0(0000) GS:ffff88807ec00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb0b5640000 CR3: 0000000046f26000 CR4: 0000000000350ee0
----------------
Code disassembly (best guess):
0: 49 8d 7d 68 lea 0x68(%r13),%rdi
4: 48 89 fa mov %rdi,%rdx
7: 48 c1 ea 03 shr $0x3,%rdx
b: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
f: 0f 85 60 02 00 00 jne 0x275
15: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1c: fc ff df
1f: 4d 8b 6d 68 mov 0x68(%r13),%r13
23: 4c 89 ea mov %r13,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 34 02 00 00 jne 0x268
34: 4d 8b 7d 00 mov 0x0(%r13),%r15
38: 4c 8d 73 0c lea 0xc(%rbx),%r14
3c: 41 rex.B
3d: bd .byte 0xbd
3e: 1f (bad)

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