================================================================== 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 ffff888094854448 by task syz-executor.2/15893 CPU: 0 PID: 15893 Comm: syz-executor.2 Not tainted 4.19.118-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:1323 con_flush drivers/tty/vt/vt.c:2546 [inline] do_con_write.part.0+0xf37/0x1db0 drivers/tty/vt/vt.c:2796 do_con_write drivers/tty/vt/vt.c:2565 [inline] con_write+0x41/0xe0 drivers/tty/vt/vt.c:3132 process_output_block drivers/tty/n_tty.c:593 [inline] n_tty_write+0x3ee/0x1080 drivers/tty/n_tty.c:2331 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: 0033:0x45c829 Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fae4badfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 000000000050cfc0 RCX: 000000000045c829 RDX: 0000000000000001 RSI: 0000000020000080 RDI: 0000000000000003 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000d14 R14: 00000000004cb1f4 R15: 00007fae4bae06d4 Allocated by task 15598: 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 __do_kmalloc_node mm/slab.c:3689 [inline] __kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3703 __kmalloc_reserve.isra.0+0x39/0xe0 net/core/skbuff.c:137 __alloc_skb+0xef/0x5b0 net/core/skbuff.c:205 alloc_skb include/linux/skbuff.h:995 [inline] alloc_skb_with_frags+0x92/0x560 net/core/skbuff.c:5303 sock_alloc_send_pskb+0x6b9/0x810 net/core/sock.c:2088 llc_ui_sendmsg+0x2fa/0xfd0 net/llc/af_llc.c:938 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:632 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2115 __sys_sendmmsg+0x195/0x470 net/socket.c:2210 __do_sys_sendmmsg net/socket.c:2239 [inline] __se_sys_sendmmsg net/socket.c:2236 [inline] __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2236 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 15598: 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 skb_free_head+0x91/0xb0 net/core/skbuff.c:554 skb_release_data+0x600/0x8c0 net/core/skbuff.c:574 skb_release_all+0x46/0x60 net/core/skbuff.c:631 __kfree_skb net/core/skbuff.c:645 [inline] kfree_skb net/core/skbuff.c:663 [inline] kfree_skb+0xe1/0x390 net/core/skbuff.c:657 llc_sap_state_process+0x8a/0x4d0 net/llc/llc_sap.c:217 llc_ui_sendmsg+0x9d4/0xfd0 net/llc/af_llc.c:961 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:632 ___sys_sendmsg+0x3e2/0x920 net/socket.c:2115 __sys_sendmmsg+0x195/0x470 net/socket.c:2210 __do_sys_sendmmsg net/socket.c:2239 [inline] __se_sys_sendmmsg net/socket.c:2236 [inline] __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2236 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8880948542c0 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 392 bytes inside of 512-byte region [ffff8880948542c0, ffff8880948544c0) The buggy address belongs to the page: page:ffffea0002521500 count:1 mapcount:0 mapping:ffff88812c39c940 index:0x0 flags: 0xfffe0000000100(slab) raw: 00fffe0000000100 ffffea000254eec8 ffffea00022e2788 ffff88812c39c940 raw: 0000000000000000 ffff888094854040 0000000100000006 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888094854300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888094854380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888094854400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888094854480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff888094854500: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ==================================================================