================================================================== BUG: KASAN: vmalloc-out-of-bounds in fb_write_offset drivers/video/fbdev/core/sysmem.h:30 [inline] BUG: KASAN: vmalloc-out-of-bounds in fb_bitmap_2ppw drivers/video/fbdev/core/fb_imageblit.h:364 [inline] BUG: KASAN: vmalloc-out-of-bounds in fb_bitmap_imageblit drivers/video/fbdev/core/fb_imageblit.h:462 [inline] BUG: KASAN: vmalloc-out-of-bounds in fb_imageblit drivers/video/fbdev/core/fb_imageblit.h:492 [inline] BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0x19fb/0x1d60 drivers/video/fbdev/core/sysimgblt.c:24 Write of size 8 at addr ffffc90004a41000 by task syz.3.578/8685 CPU: 0 UID: 0 PID: 8685 Comm: syz.3.578 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 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/0x1d0 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 set_cursor drivers/tty/vt/vt.c:896 [inline] set_cursor+0x1db/0x250 drivers/tty/vt/vt.c:887 con_flush_chars drivers/tty/vt/vt.c:3730 [inline] con_write+0x89/0xb0 drivers/tty/vt/vt.c:3661 do_output_char+0x63b/0x850 drivers/tty/n_tty.c:418 process_output drivers/tty/n_tty.c:482 [inline] n_tty_write+0x4e8/0x11c0 drivers/tty/n_tty.c:2377 iterate_tty_write drivers/tty/tty_io.c:1006 [inline] file_tty_write.isra.0+0x4d2/0x890 drivers/tty/tty_io.c:1081 tty_write drivers/tty/tty_io.c:1102 [inline] redirected_tty_write drivers/tty/tty_io.c:1125 [inline] redirected_tty_write+0xd4/0x120 drivers/tty/tty_io.c:1105 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+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f85d9f9ce59 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:00007f85dad9d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f85da215fa0 RCX: 00007f85d9f9ce59 RDX: 000000000000fdef RSI: 0000200000000000 RDI: 0000000000000000 RBP: 00007f85da032d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f85da216038 R14: 00007f85da215fa0 R15: 00007ffc49e1fcd8 The buggy address belongs to a 0-page vmalloc region starting at 0xffffc90004741000 allocated at drm_gem_shmem_vmap_locked+0x553/0x860 drivers/gpu/drm/drm_gem_shmem_helper.c:395 Memory state around the buggy address: ffffc90004a40f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffffc90004a40f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffffc90004a41000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffffc90004a41080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90004a41100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ==================================================================