================================================================== BUG: KASAN: use-after-free in __fb_pad_aligned_buffer include/linux/fb.h:674 [inline] BUG: KASAN: use-after-free in bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline] BUG: KASAN: use-after-free in bit_putcs+0xc74/0xe10 drivers/video/fbdev/core/bitblit.c:185 Read of size 1 at addr ffff888088ddb457 by task syz-executor.0/12806 CPU: 1 PID: 12806 Comm: syz-executor.0 Not tainted 4.19.111-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 print_address_description.cold+0x7c/0x212 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold+0x88/0x2b9 mm/kasan/report.c:396 __fb_pad_aligned_buffer include/linux/fb.h:674 [inline] bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline] bit_putcs+0xc74/0xe10 drivers/video/fbdev/core/bitblit.c:185 fbcon_putcs+0x434/0x4f0 drivers/video/fbdev/core/fbcon.c:1320 con_flush drivers/tty/vt/vt.c:2533 [inline] do_con_write.part.0+0xf37/0x1db0 drivers/tty/vt/vt.c:2783 do_con_write drivers/tty/vt/vt.c:2552 [inline] con_write+0x41/0xe0 drivers/tty/vt/vt.c:3119 n_tty_write+0xa69/0x1080 drivers/tty/n_tty.c:2354 do_tty_write drivers/tty/tty_io.c:960 [inline] tty_write+0x452/0x790 drivers/tty/tty_io.c:1044 do_loop_readv_writev fs/read_write.c:704 [inline] do_loop_readv_writev fs/read_write.c:688 [inline] do_iter_write fs/read_write.c:962 [inline] do_iter_write+0x460/0x5e0 fs/read_write.c:941 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1005 do_writev+0x136/0x330 fs/read_write.c:1040 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c849 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fea3c0ebc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007fea3c0ec6d4 RCX: 000000000045c849 RDX: 0000000000000001 RSI: 00000000200005c0 RDI: 0000000000000003 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000d12 R14: 00000000004cb19d R15: 000000000076bf0c Allocated by task 18759: set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc mm/kasan/kasan.c:553 [inline] kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:531 kmem_cache_alloc_trace+0x14d/0x7a0 mm/slab.c:3625 kmalloc include/linux/slab.h:515 [inline] kzalloc include/linux/slab.h:709 [inline] ep_alloc fs/eventpoll.c:1021 [inline] do_epoll_create+0xcd/0x380 fs/eventpoll.c:1960 __do_sys_epoll_create1 fs/eventpoll.c:1991 [inline] __se_sys_epoll_create1 fs/eventpoll.c:1989 [inline] __x64_sys_epoll_create1+0x2d/0x40 fs/eventpoll.c:1989 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 18759: set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0xf7/0x140 mm/kasan/kasan.c:521 __cache_free mm/slab.c:3503 [inline] kfree+0xce/0x220 mm/slab.c:3822 ep_eventpoll_release+0x41/0x60 fs/eventpoll.c:869 __fput+0x2cd/0x890 fs/file_table.c:278 task_work_run+0x13f/0x1b0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:193 [inline] exit_to_usermode_loop+0x25a/0x2b0 arch/x86/entry/common.c:167 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline] syscall_return_slowpath arch/x86/entry/common.c:271 [inline] do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888088ddb340 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 279 bytes inside of 512-byte region [ffff888088ddb340, ffff888088ddb540) The buggy address belongs to the page: page:ffffea00022376c0 count:1 mapcount:0 mapping:ffff88812c3dc940 index:0xffff888088ddb840 flags: 0xfffe0000000100(slab) raw: 00fffe0000000100 ffffea0002609e88 ffffea0002a3e7c8 ffff88812c3dc940 raw: ffff888088ddb840 ffff888088ddb0c0 0000000100000004 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888088ddb300: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff888088ddb380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888088ddb400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888088ddb480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888088ddb500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================