================================================================== BUG: KASAN: stack-out-of-bounds in fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline] BUG: KASAN: stack-out-of-bounds in fb_bitmap_2ppw drivers/video/fbdev/core/fb_imageblit.h:364 [inline] BUG: KASAN: stack-out-of-bounds in fb_bitmap_imageblit drivers/video/fbdev/core/fb_imageblit.h:462 [inline] BUG: KASAN: stack-out-of-bounds in fb_imageblit drivers/video/fbdev/core/fb_imageblit.h:492 [inline] BUG: KASAN: stack-out-of-bounds in sys_imageblit+0x19fb/0x1d60 drivers/video/fbdev/core/sysimgblt.c:24 Write of size 8 at addr ffffc9000484fbe0 by task syz.0.14433/3769 CPU: 0 UID: 0 PID: 3769 Comm: syz.0.14433 Tainted: G U L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 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+0x13d/0x4b0 mm/kasan/report.c:482 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595 fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline] fb_bitmap_2ppw drivers/video/fbdev/core/fb_imageblit.h:364 [inline] fb_bitmap_imageblit drivers/video/fbdev/core/fb_imageblit.h:462 [inline] fb_imageblit drivers/video/fbdev/core/fb_imageblit.h:492 [inline] sys_imageblit+0x19fb/0x1d60 drivers/video/fbdev/core/sysimgblt.c:24 drm_fbdev_shmem_defio_imageblit+0x20/0x130 drivers/gpu/drm/drm_fbdev_shmem.c:39 soft_cursor+0x524/0xa10 drivers/video/fbdev/core/softcursor.c:74 bit_cursor+0xca1/0x1490 drivers/video/fbdev/core/bitblit.c:365 fbcon_cursor+0x43c/0x5e0 drivers/video/fbdev/core/fbcon.c:1427 hide_cursor+0x87/0x230 drivers/tty/vt/vt.c:883 putconsxy+0x1f/0x3c0 drivers/tty/vt/vt.c:5088 vcs_write_buf drivers/tty/vt/vc_screen.c:530 [inline] vcs_write+0xbd5/0xd70 drivers/tty/vt/vc_screen.c:674 vfs_write+0x2aa/0x1050 fs/read_write.c:685 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe7a299de59 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:00007fe7a0bf6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fe7a2c25fa0 RCX: 00007fe7a299de59 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007fe7a2a33e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe7a2c26038 R14: 00007fe7a2c25fa0 R15: 00007ffd16e6ef68 The buggy address belongs to a vmalloc virtual mapping The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32b57 memcg:ffff88803394db02 flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000001ffffffff ffff88803394db02 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x29c2(GFP_NOWAIT|__GFP_HIGHMEM|__GFP_IO|__GFP_FS|__GFP_ZERO), pid 5999, tgid 5999 (syz-executor), ts 1014602920947, free_ts 1014536727158 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859 prep_new_page mm/page_alloc.c:1867 [inline] get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946 __alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304 alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2490 alloc_pages_noprof+0x1a/0x160 mm/mempolicy.c:2581 vm_area_alloc_pages mm/vmalloc.c:3667 [inline] __vmalloc_area_node mm/vmalloc.c:3892 [inline] __vmalloc_node_range_noprof+0xf9a/0x1630 mm/vmalloc.c:4082 __vmalloc_node_noprof+0xad/0xf0 mm/vmalloc.c:4143 alloc_thread_stack_node kernel/fork.c:359 [inline] dup_task_struct kernel/fork.c:929 [inline] copy_process+0x7fb/0x8030 kernel/fork.c:2115 kernel_clone+0x176/0x9d0 kernel/fork.c:2748 __do_sys_clone+0xd9/0x120 kernel/fork.c:2889 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 23793 tgid 23793 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1406 [inline] __free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4612 [inline] slab_alloc_node mm/slub.c:4945 [inline] kmem_cache_alloc_noprof+0x26b/0x6a0 mm/slub.c:4959 ext4_init_io_end+0x24/0x170 fs/ext4/page-io.c:310 ext4_do_writepages+0x9cf/0x3ed0 fs/ext4/inode.c:2890 ext4_writepages+0x347/0x750 fs/ext4/inode.c:3043 do_writepages+0x278/0x600 mm/page-writeback.c:2571 __writeback_single_inode+0x164/0x1300 fs/fs-writeback.c:1787 writeback_sb_inodes+0x766/0x1c50 fs/fs-writeback.c:2079 __writeback_inodes_wb+0xf8/0x2d0 fs/fs-writeback.c:2155 wb_writeback+0x6f6/0xb50 fs/fs-writeback.c:2266 wb_check_background_flush fs/fs-writeback.c:2336 [inline] wb_do_writeback fs/fs-writeback.c:2450 [inline] wb_workfn+0x7cb/0xc80 fs/fs-writeback.c:2477 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 Memory state around the buggy address: ffffc9000484fa80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffffc9000484fb00: 00 00 f1 f1 f1 f1 f1 f1 00 00 00 00 00 00 00 00 >ffffc9000484fb80: 00 00 00 00 00 00 00 00 00 f3 f3 f3 f3 f3 f3 f3 ^ ffffc9000484fc00: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 ffffc9000484fc80: f1 f1 f1 00 00 00 00 00 00 00 00 00 00 00 f3 f3 ==================================================================