linux-kernel - Re: [syzbot] [usb?] general protection fault in status

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Message-ID: <6791725a.050a0220.194594.001f.GAE@google.com>
Date: Wed, 22 Jan 2025 14:34:02 -0800
From: syzbot <syzbot+83976e47ec1ef91e66f1@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, skhan@...uxfoundation.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [usb?] general protection fault in status_show

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in status_show

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000081: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000408-0x000000000000040f]
CPU: 1 UID: 0 PID: 6590 Comm: syz.0.16 Not tainted 6.13.0-syzkaller-g70ef2d3a2cfe #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:status_show_vhci drivers/usb/usbip/vhci_sysfs.c:80 [inline]
RIP: 0010:status_show+0x33c/0x610 drivers/usb/usbip/vhci_sysfs.c:160
Code: 03 80 3c 02 00 0f 85 d8 02 00 00 48 8b 9b 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d bb 08 04 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 8a 02 00 00 4c 8b b3 08 04 00 00 41 c1 e7 04 31
RSP: 0018:ffffc90003437ad8 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8753624b
RDX: 0000000000000081 RSI: ffffffff875363fb RDI: 0000000000000408
RBP: ffff888060944000 R08: 0000000000000004 R09: 0000000000000010
R10: 000000000000000f R11: 64666b636f732020 R12: 1ffff92000686f61
R13: ffffc90003437b28 R14: ffff88806094402d R15: 000000000000000f
FS:  00007f7f21b996c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f25ffff CR3: 00000000274d2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 dev_attr_show+0x53/0xe0 drivers/base/core.c:2423
 sysfs_kf_seq_show+0x223/0x3e0 fs/sysfs/file.c:59
 seq_read_iter+0x4f4/0x12b0 fs/seq_file.c:230
 kernfs_fop_read_iter+0x414/0x580 fs/kernfs/file.c:279
 new_sync_read fs/read_write.c:484 [inline]
 vfs_read+0x87f/0xbe0 fs/read_write.c:565
 ksys_read+0x12b/0x250 fs/read_write.c:708
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7f20d85d29
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7f21b99038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f7f20f75fa0 RCX: 00007f7f20d85d29
RDX: 0000000000000062 RSI: 0000000020001080 RDI: 0000000000000003
RBP: 00007f7f20e01b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f7f20f75fa0 R15: 00007ffe7ae1a108
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:status_show_vhci drivers/usb/usbip/vhci_sysfs.c:80 [inline]
RIP: 0010:status_show+0x33c/0x610 drivers/usb/usbip/vhci_sysfs.c:160
Code: 03 80 3c 02 00 0f 85 d8 02 00 00 48 8b 9b 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d bb 08 04 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 8a 02 00 00 4c 8b b3 08 04 00 00 41 c1 e7 04 31
RSP: 0018:ffffc90003437ad8 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff8753624b
RDX: 0000000000000081 RSI: ffffffff875363fb RDI: 0000000000000408
RBP: ffff888060944000 R08: 0000000000000004 R09: 0000000000000010
R10: 000000000000000f R11: 64666b636f732020 R12: 1ffff92000686f61
R13: ffffc90003437b28 R14: ffff88806094402d R15: 000000000000000f
FS:  00007f7f21b996c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0053c575e8 CR3: 00000000274d2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	03 80 3c 02 00 0f    	add    0xf00023c(%rax),%eax
   6:	85 d8                	test   %ebx,%eax
   8:	02 00                	add    (%rax),%al
   a:	00 48 8b             	add    %cl,-0x75(%rax)
   d:	9b                   	fwait
   e:	88 00                	mov    %al,(%rax)
  10:	00 00                	add    %al,(%rax)
  12:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  19:	fc ff df
  1c:	48 8d bb 08 04 00 00 	lea    0x408(%rbx),%rdi
  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 8a 02 00 00    	jne    0x2be
  34:	4c 8b b3 08 04 00 00 	mov    0x408(%rbx),%r14
  3b:	41 c1 e7 04          	shl    $0x4,%r15d
  3f:	31                   	.byte 0x31


Tested on:

commit:         70ef2d3a usbip/vhci: Fix general protection error
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux.git usbip_test
console output: https://syzkaller.appspot.com/x/log.txt?x=149325df980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fdfc8dd0ccb1401a
dashboard link: https://syzkaller.appspot.com/bug?extid=83976e47ec1ef91e66f1
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.