Re: [syzbot] [kernel?] general protection fault in nfc_register_device

[syzbot <syzbot+bdfb03b1ec8b342c12cb@syzkaller.appspotmail.com>]

Hello,

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

RBP: 00007fad795a4120 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 000000000000000b R14: 00007fad7899bf80 R15: 00007fffcac52128
 </TASK>
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: 5480 Comm: syz-executor.0 Not tainted 6.5.0-rc7-next-20230825-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
RIP: 0010:strchr+0x1b/0xb0 lib/string.c:329
Code: ad ac f7 48 8b 74 24 08 48 8b 14 24 eb 89 90 f3 0f 1e fa 48 b8 00 00 00 00 00 fc ff df 48 89 fa 55 48 c1 ea 03 53 48 83 ec 10 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 04 84 c0 75 51 0f b6 07 89
RSP: 0018:ffffc90004def630 EFLAGS: 00010286
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000025 RDI: 0000000000000000
RBP: ffffc90004def6c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffc90004def6c0
R13: 0000000000000cc0 R14: ffff8881413d4a00 R15: 0000000000000001
FS:  00007fad795a46c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fad795a3ff8 CR3: 00000000294b2000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kvasprintf_const+0x25/0x190 lib/kasprintf.c:45
 kobject_set_name_vargs+0x5a/0x130 lib/kobject.c:272
 kobject_add_varg lib/kobject.c:366 [inline]
 kobject_add+0x12a/0x240 lib/kobject.c:424
 device_add+0x2a1/0x1aa0 drivers/base/core.c:3562
 nfc_register_device+0x41/0x3c0 net/nfc/core.c:1118
 nci_register_device+0x7f4/0xb80 net/nfc/nci/core.c:1257
 virtual_ncidev_open+0x147/0x220 drivers/nfc/virtual_ncidev.c:148
 misc_open+0x3da/0x4c0 drivers/char/misc.c:165
 chrdev_open+0x277/0x700 fs/char_dev.c:414
 do_dentry_open+0x88b/0x1730 fs/open.c:929
 do_open fs/namei.c:3639 [inline]
 path_openat+0x19af/0x29c0 fs/namei.c:3796
 do_filp_open+0x1de/0x430 fs/namei.c:3823
 do_sys_openat2+0x176/0x1e0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fad7887cae9
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:00007fad795a40c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fad7899bf80 RCX: 00007fad7887cae9
RDX: 0000000000000002 RSI: 0000000020000000 RDI: ffffffffffffff9c
RBP: 00007fad795a4120 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 000000000000000b R14: 00007fad7899bf80 R15: 00007fffcac52128
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:strchr+0x1b/0xb0 lib/string.c:329
Code: ad ac f7 48 8b 74 24 08 48 8b 14 24 eb 89 90 f3 0f 1e fa 48 b8 00 00 00 00 00 fc ff df 48 89 fa 55 48 c1 ea 03 53 48 83 ec 10 <0f> b6 04 02 48 89 fa 83 e2 07 38 d0 7f 04 84 c0 75 51 0f b6 07 89
RSP: 0018:ffffc90004def630 EFLAGS: 00010286
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000025 RDI: 0000000000000000
RBP: ffffc90004def6c0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffc90004def6c0
R13: 0000000000000cc0 R14: ffff8881413d4a00 R15: 0000000000000001
FS:  00007fad795a46c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff66020268 CR3: 00000000294b2000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	ad                   	lods   %ds:(%rsi),%eax
   1:	ac                   	lods   %ds:(%rsi),%al
   2:	f7 48 8b 74 24 08 48 	testl  $0x48082474,-0x75(%rax)
   9:	8b 14 24             	mov    (%rsp),%edx
   c:	eb 89                	jmp    0xffffff97
   e:	90                   	nop
   f:	f3 0f 1e fa          	endbr64
  13:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  1a:	fc ff df
  1d:	48 89 fa             	mov    %rdi,%rdx
  20:	55                   	push   %rbp
  21:	48 c1 ea 03          	shr    $0x3,%rdx
  25:	53                   	push   %rbx
  26:	48 83 ec 10          	sub    $0x10,%rsp
* 2a:	0f b6 04 02          	movzbl (%rdx,%rax,1),%eax <-- trapping instruction
  2e:	48 89 fa             	mov    %rdi,%rdx
  31:	83 e2 07             	and    $0x7,%edx
  34:	38 d0                	cmp    %dl,%al
  36:	7f 04                	jg     0x3c
  38:	84 c0                	test   %al,%al
  3a:	75 51                	jne    0x8d
  3c:	0f b6 07             	movzbl (%rdi),%eax
  3f:	89                   	.byte 0x89


Tested on:

commit:         62693208 Add linux-next specific files for 20230825
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=15ac67b7a80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8a8c992a790e5073
dashboard link: https://syzkaller.appspot.com/bug?extid=bdfb03b1ec8b342c12cb
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1254f9eba80000