syzbot


general protection fault in fbcon_new_modelist

Status: moderation: reported on 2025/02/08 22:44
Subsystems: fbdev
[Documentation on labels]
Reported-by: syzbot+7a3acc3b02a7a9d799b3@syzkaller.appspotmail.com
First crash: 16d, last: 16d

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000078: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x00000000000003c0-0x00000000000003c7]
CPU: 1 UID: 0 PID: 11237 Comm: syz.0.1298 Tainted: G     U             6.14.0-rc1-syzkaller-00026-gd009de7d5428 #0
Tainted: [U]=USER
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:fbcon_new_modelist+0x1b5/0x2d0 drivers/video/fbdev/core/fbcon.c:3057
Code: d6 48 8b b8 f0 63 ac 9a e8 18 24 fe ff 4c 89 f7 48 89 c6 e8 ed 17 fe ff 48 8b 04 24 48 8d b8 c0 03 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 74 08 3c 01 0f 8e c0 00 00 00 48 8b 04 24 4c
RSP: 0018:ffffc9000260f878 EFLAGS: 00010206
RAX: 0000000000000078 RBX: 000000000000000a RCX: ffffc90005773000
RDX: 0000000000000000 RSI: ffffffff850181d3 RDI: 00000000000003c0
RBP: ffffffff9aac68a0 R08: 0000000000000004 R09: 0000000000000498
R10: 00000000ffffffff R11: 0000000000000006 R12: ffff888142fd6000
R13: dffffc0000000000 R14: ffffc9000260f8b0 R15: 000000000000000a
FS:  00007fa6fb5d96c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b303eaff8 CR3: 000000002a7f4000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 fb_new_modelist+0x328/0x440 drivers/video/fbdev/core/fbmem.c:673
 store_modes+0x1c9/0x3e0 drivers/video/fbdev/core/fbsysfs.c:113
 dev_attr_store+0x55/0x80 drivers/base/core.c:2439
 sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:139
 kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0x5ae/0x1150 fs/read_write.c:679
 ksys_write+0x12b/0x250 fs/read_write.c:731
 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: 0033:0x7fa6fa78cda9
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:00007fa6fb5d9038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fa6fa9a5fa0 RCX: 00007fa6fa78cda9
RDX: 000000000000a3d9 RSI: 0000000020000400 RDI: 0000000000000005
RBP: 00007fa6fa80e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fa6fa9a5fa0 R15: 00007ffc106fb548
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:fbcon_new_modelist+0x1b5/0x2d0 drivers/video/fbdev/core/fbcon.c:3057
Code: d6 48 8b b8 f0 63 ac 9a e8 18 24 fe ff 4c 89 f7 48 89 c6 e8 ed 17 fe ff 48 8b 04 24 48 8d b8 c0 03 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 74 08 3c 01 0f 8e c0 00 00 00 48 8b 04 24 4c
RSP: 0018:ffffc9000260f878 EFLAGS: 00010206
RAX: 0000000000000078 RBX: 000000000000000a RCX: ffffc90005773000
RDX: 0000000000000000 RSI: ffffffff850181d3 RDI: 00000000000003c0
RBP: ffffffff9aac68a0 R08: 0000000000000004 R09: 0000000000000498
R10: 00000000ffffffff R11: 0000000000000006 R12: ffff888142fd6000
R13: dffffc0000000000 R14: ffffc9000260f8b0 R15: 000000000000000a
FS:  00007fa6fb5d96c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b303eaff8 CR3: 000000002a7f4000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	48 8b b8 f0 63 ac 9a 	mov    -0x65539c10(%rax),%rdi
   7:	e8 18 24 fe ff       	call   0xfffe2424
   c:	4c 89 f7             	mov    %r14,%rdi
   f:	48 89 c6             	mov    %rax,%rsi
  12:	e8 ed 17 fe ff       	call   0xfffe1804
  17:	48 8b 04 24          	mov    (%rsp),%rax
  1b:	48 8d b8 c0 03 00 00 	lea    0x3c0(%rax),%rdi
  22:	48 89 f8             	mov    %rdi,%rax
  25:	48 c1 e8 03          	shr    $0x3,%rax
* 29:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	74 08                	je     0x3a
  32:	3c 01                	cmp    $0x1,%al
  34:	0f 8e c0 00 00 00    	jle    0xfa
  3a:	48 8b 04 24          	mov    (%rsp),%rax
  3e:	4c                   	rex.WR

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/04 22:37 upstream d009de7d5428 44c01590 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto general protection fault in fbcon_new_modelist
* Struck through repros no longer work on HEAD.