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UBSAN: array-index-out-of-bounds in fbcon_info_from_console

Status: upstream: reported on 2025/01/31 17:38
Subsystems: fbdev
[Documentation on labels]
Reported-by: syzbot+a7d4444e7b6e743572f7@syzkaller.appspotmail.com
First crash: 8d13h, last: 21h23m
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [fbdev?] UBSAN: array-index-out-of-bounds in fbcon_info_from_console 0 (1) 2025/01/31 17:38

Sample crash report:
------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in drivers/video/fbdev/core/fbcon.c:122:28
index -1 is out of range for type 'fb_info *[32]'
CPU: 1 UID: 0 PID: 7790 Comm: syz.1.368 Not tainted 6.14.0-rc1-syzkaller-00020-g0de63bb7d919 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:231 [inline]
 __ubsan_handle_out_of_bounds+0x110/0x150 lib/ubsan.c:429
 fbcon_info_from_console+0x192/0x1a0 drivers/video/fbdev/core/fbcon.c:122
 fbcon_new_modelist+0xbf/0x2d0 drivers/video/fbdev/core/fbcon.c:3048
 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: 0033:0x7fc8e318cda9
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:00007fc8e3fc1038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc8e33a5fa0 RCX: 00007fc8e318cda9
RDX: 000000000000a3d9 RSI: 0000000020000400 RDI: 0000000000000002
RBP: 00007fc8e320e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc8e33a5fa0 R15: 00007ffcf7f131c8
 </TASK>
---[ end trace ]---

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/04 09:25 upstream 0de63bb7d919 8f267cef .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto UBSAN: array-index-out-of-bounds in fbcon_info_from_console
2025/02/04 09:06 upstream 0de63bb7d919 8f267cef .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto UBSAN: array-index-out-of-bounds in fbcon_info_from_console
2025/01/27 17:35 upstream 9c5968db9e62 d99a33ad .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto UBSAN: array-index-out-of-bounds in fbcon_info_from_console
* Struck through repros no longer work on HEAD.