[moderation] [fbdev?] general protection fault in fbcon_new_modelist

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d009de7d5428 Merge tag 'livepatching-for-6.14-rc2' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=151edd18580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c48f582603dcb16c
dashboard link: https://syzkaller.appspot.com/bug?extid=7a3acc3b02a7a9d799b3
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [del...@gmx.de dri-...@lists.freedesktop.org linux...@vger.kernel.org linux-...@vger.kernel.org sim...@ffwll.ch]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2596537b4af9/disk-d009de7d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f451a9ee994c/vmlinux-d009de7d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f1b4673832e3/bzImage-d009de7d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7a3acc...@syzkaller.appspotmail.com

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


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.