Hello, syzbot found the following issue on: HEAD commit: d082ecbc71e9 Linux 6.14-rc4 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=100c97a4580000 kernel config: https://syzkaller.appspot.com/x/.config?x=b1635bf4c5557b92 dashboard link: https://syzkaller.appspot.com/bug?extid=0c815b25cdb3678e7083 compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/323a5d590eec/disk-d082ecbc.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/f7c4b6e33fd9/vmlinux-d082ecbc.xz kernel image: https://storage.googleapis.com/syzbot-assets/c518bbd55334/bzImage-d082ecbc.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+0c815b25cdb3678e7083@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== BUG: KASAN: slab-out-of-bounds in scr_memcpyw include/linux/vt_buffer.h:38 [inline] BUG: KASAN: slab-out-of-bounds in fbcon_prepare_logo+0xa15/0xc80 drivers/video/fbdev/core/fbcon.c:614 Read of size 256 at addr ffff888033e96f60 by task syz.0.317/7285 CPU: 1 UID: 0 PID: 7285 Comm: syz.0.317 Not tainted 6.14.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xd9/0x110 mm/kasan/report.c:634 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189 __asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105 scr_memcpyw include/linux/vt_buffer.h:38 [inline] fbcon_prepare_logo+0xa15/0xc80 drivers/video/fbdev/core/fbcon.c:614 fbcon_init+0xd41/0x1890 drivers/video/fbdev/core/fbcon.c:1146 visual_init+0x31d/0x620 drivers/tty/vt/vt.c:1011 do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3831 vt_bind drivers/tty/vt/vt.c:3987 [inline] store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059 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: 0033:0x7f44b6f8d169 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:00007f44b7dc3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f44b71a5fa0 RCX: 00007f44b6f8d169 RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007f44b700e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f44b71a5fa0 R15: 00007ffee813d3a8 </TASK> The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888033e94340 pfn:0x33e94 head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000040 0000000000000000 dead000000000122 0000000000000000 raw: ffff888033e94340 0000000000000000 00000001ffffffff 0000000000000000 head: 00fff00000000040 0000000000000000 dead000000000122 0000000000000000 head: ffff888033e94340 0000000000000000 00000001ffffffff 0000000000000000 head: 00fff00000000002 ffffea0000cfa501 ffffffffffffffff 0000000000000000 head: 0000000000000004 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0x140dc0(GFP_USER|__GFP_COMP|__GFP_ZERO), pid 7285, tgid 7284 (syz.0.317), ts 193263994848, free_ts 193235941647 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1551 prep_new_page mm/page_alloc.c:1559 [inline] get_page_from_freelist+0xfce/0x2f80 mm/page_alloc.c:3477 __alloc_frozen_pages_noprof+0x221/0x2470 mm/page_alloc.c:4739 __alloc_pages_noprof+0xb/0x1b0 mm/page_alloc.c:4773 __alloc_pages_node_noprof include/linux/gfp.h:265 [inline] alloc_pages_node_noprof include/linux/gfp.h:292 [inline] ___kmalloc_large_node+0x84/0x1b0 mm/slub.c:4239 __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:4266 __do_kmalloc_node mm/slub.c:4282 [inline] __kmalloc_noprof.cold+0xc/0x61 mm/slub.c:4306 kmalloc_noprof include/linux/slab.h:905 [inline] kzalloc_noprof include/linux/slab.h:1037 [inline] vc_do_resize+0x1e3/0x10f0 drivers/tty/vt/vt.c:1174 vc_resize include/linux/vt_kern.h:49 [inline] fbcon_init+0xd1d/0x1890 drivers/video/fbdev/core/fbcon.c:1143 visual_init+0x31d/0x620 drivers/tty/vt/vt.c:1011 do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3831 vt_bind drivers/tty/vt/vt.c:3987 [inline] store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059 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 page last free pid 7285 tgid 7284 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1127 [inline] free_frozen_pages+0x6db/0xfb0 mm/page_alloc.c:2660 __folio_put+0x32a/0x450 mm/swap.c:112 vc_do_resize+0xe31/0x10f0 drivers/tty/vt/vt.c:1194 vc_resize include/linux/vt_kern.h:49 [inline] fbcon_startup+0x406/0xb70 drivers/video/fbdev/core/fbcon.c:997 do_bind_con_driver.isra.0+0x207/0xbf0 drivers/tty/vt/vt.c:3794 vt_bind drivers/tty/vt/vt.c:3987 [inline] store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059 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 Memory state around the buggy address: ffff888033e96f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888033e96f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888033e97000: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe ^ ffff888033e97080: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe ffff888033e97100: fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe fe ================================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
