================================================================== 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+0x94e/0xc60 drivers/video/fbdev/core/fbcon.c:646 Read of size 26 at addr ffff888027f92fea by task syz.5.3686/16746 CPU: 0 UID: 0 PID: 16746 Comm: syz.5.3686 Tainted: G U L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x156/0x4c9 mm/kasan/report.c:482 kasan_report+0xdf/0x1e0 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:186 [inline] kasan_check_range+0x10f/0x1e0 mm/kasan/generic.c:200 __asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105 scr_memcpyw include/linux/vt_buffer.h:38 [inline] fbcon_prepare_logo+0x94e/0xc60 drivers/video/fbdev/core/fbcon.c:646 fbcon_init+0x10a0/0x1820 drivers/video/fbdev/core/fbcon.c:1180 visual_init+0x320/0x620 drivers/tty/vt/vt.c:1014 do_bind_con_driver.isra.0+0x636/0x9c0 drivers/tty/vt/vt.c:3954 vt_bind drivers/tty/vt/vt.c:4110 [inline] store_bind+0x609/0x730 drivers/tty/vt/vt.c:4182 dev_attr_store+0x58/0x80 drivers/base/core.c:2437 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7b7bd9c799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f7b7cce6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f7b7c016090 RCX: 00007f7b7bd9c799 RDX: 0000000000000084 RSI: 0000200000000040 RDI: 0000000000000003 RBP: 00007f7b7be32c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f7b7c016128 R14: 00007f7b7c016090 R15: 00007ffc6c4364e8 Allocated by task 10831: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __do_kmalloc_node mm/slub.c:5260 [inline] __kmalloc_node_noprof+0x307/0x850 mm/slub.c:5266 kmalloc_node_noprof include/linux/slab.h:1081 [inline] alloc_slab_obj_exts+0xae/0x260 mm/slub.c:2167 __memcg_slab_post_alloc_hook+0x246/0x990 mm/memcontrol.c:3234 memcg_slab_post_alloc_hook mm/slub.c:2457 [inline] slab_post_alloc_hook mm/slub.c:4549 [inline] slab_alloc_node mm/slub.c:4866 [inline] kmem_cache_alloc_lru_noprof+0x592/0x6e0 mm/slub.c:4885 shmem_alloc_inode+0x25/0x50 mm/shmem.c:5167 alloc_inode+0x68/0x250 fs/inode.c:347 new_inode+0x22/0x1c0 fs/inode.c:1185 __shmem_get_inode mm/shmem.c:3079 [inline] shmem_get_inode+0x212/0x1040 mm/shmem.c:3154 shmem_symlink+0x11b/0xa00 mm/shmem.c:4117 vfs_symlink fs/namei.c:5615 [inline] vfs_symlink+0x178/0x4d0 fs/namei.c:5594 filename_symlinkat+0x2a6/0x560 fs/namei.c:5640 __do_sys_symlinkat fs/namei.c:5660 [inline] __se_sys_symlinkat fs/namei.c:5655 [inline] __x64_sys_symlinkat+0x9c/0xe0 fs/namei.c:5655 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888027f92f00 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 82 bytes to the right of allocated 152-byte region [ffff888027f92f00, ffff888027f92f98) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x27f92 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000000 ffff88813fe3c3c0 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 7254, tgid 7253 (syz.0.256), ts 141426517229, free_ts 140354263219 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x153/0x170 mm/page_alloc.c:1889 prep_new_page mm/page_alloc.c:1897 [inline] get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3962 __alloc_frozen_pages_noprof+0x27c/0x2ba0 mm/page_alloc.c:5250 alloc_slab_page mm/slub.c:3292 [inline] allocate_slab mm/slub.c:3481 [inline] new_slab+0xa6/0x6b0 mm/slub.c:3539 refill_objects+0x26b/0x400 mm/slub.c:7175 refill_sheaf mm/slub.c:2812 [inline] __pcs_replace_empty_main+0x1ab/0x660 mm/slub.c:4615 alloc_from_pcs mm/slub.c:4717 [inline] slab_alloc_node mm/slub.c:4851 [inline] __do_kmalloc_node mm/slub.c:5259 [inline] __kmalloc_node_noprof+0x69a/0x850 mm/slub.c:5266 kmalloc_node_noprof include/linux/slab.h:1081 [inline] alloc_slab_obj_exts+0xae/0x260 mm/slub.c:2167 __memcg_slab_post_alloc_hook+0x246/0x990 mm/memcontrol.c:3234 memcg_slab_post_alloc_hook mm/slub.c:2457 [inline] slab_post_alloc_hook mm/slub.c:4549 [inline] slab_alloc_node mm/slub.c:4866 [inline] kmem_cache_alloc_noprof+0x58a/0x6e0 mm/slub.c:4873 alloc_buffer_head+0x21/0x140 fs/buffer.c:3026 folio_alloc_buffers+0x2a0/0x8f0 fs/buffer.c:932 create_empty_buffers+0x3a/0x660 fs/buffer.c:1688 folio_create_buffers+0x13b/0x1a0 fs/buffer.c:1799 __block_write_begin_int+0x393/0x19c0 fs/buffer.c:2123 iomap_write_begin+0x1664/0x2340 fs/iomap/buffered-io.c:1009 page last free pid 7233 tgid 7229 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1433 [inline] free_unref_folios+0xaea/0x1790 mm/page_alloc.c:3040 folios_put_refs+0x53c/0x840 mm/swap.c:1002 folio_batch_release include/linux/pagevec.h:101 [inline] mapping_try_invalidate+0x2ff/0x3c0 mm/truncate.c:579 invalidate_bdev+0x8d/0xb0 block/bdev.c:102 blkdev_flushbuf block/ioctl.c:533 [inline] blkdev_common_ioctl+0xf83/0x2ba0 block/ioctl.c:665 blkdev_ioctl+0x43b/0x6f0 block/ioctl.c:798 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888027f92e80: 00 00 00 04 fc fc fc fc fc fc fc fc fc fc fc fc ffff888027f92f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888027f92f80: 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff888027f93000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888027f93080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================