================================================================== BUG: KASAN: use-after-free in __fb_pad_aligned_buffer include/linux/fb.h:655 [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+0xc08/0xd60 drivers/video/fbdev/core/bitblit.c:185 Read of size 1 at addr ffff8880a869c906 by task syz-executor.5/15404 CPU: 0 PID: 15404 Comm: syz-executor.5 Not tainted 5.7.0-rc7-next-20200529-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+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd3/0x413 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 __fb_pad_aligned_buffer include/linux/fb.h:655 [inline] bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline] bit_putcs+0xc08/0xd60 drivers/video/fbdev/core/bitblit.c:185 fbcon_putcs+0x345/0x3f0 drivers/video/fbdev/core/fbcon.c:1362 do_update_region+0x398/0x630 drivers/tty/vt/vt.c:683 redraw_screen+0x64c/0x770 drivers/tty/vt/vt.c:1029 vc_do_resize+0x1007/0x1370 drivers/tty/vt/vt.c:1314 vt_ioctl+0x200c/0x2640 drivers/tty/vt/vt_ioctl.c:901 tty_ioctl+0xedc/0x1440 drivers/tty/tty_io.c:2656 vfs_ioctl fs/ioctl.c:48 [inline] ksys_ioctl+0x11a/0x180 fs/ioctl.c:753 __do_sys_ioctl fs/ioctl.c:762 [inline] __se_sys_ioctl fs/ioctl.c:760 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45ca69 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:00007f655a1cbc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004f2b40 RCX: 000000000045ca69 RDX: 0000000020000000 RSI: 000000000000560a RDI: 0000000000000003 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000673 R14: 00000000004c96c1 R15: 00007f655a1cc6d4 Allocated by task 15010: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc mm/kasan/common.c:494 [inline] __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:467 __kmalloc_reserve.isra.0+0x39/0xe0 net/core/skbuff.c:142 __alloc_skb+0xef/0x5a0 net/core/skbuff.c:210 alloc_skb include/linux/skbuff.h:1083 [inline] alloc_skb_with_frags+0x92/0x560 net/core/skbuff.c:5770 sock_alloc_send_pskb+0x734/0x890 net/core/sock.c:2352 __ip_append_data.isra.0+0x167d/0x3270 net/ipv4/ip_output.c:1089 ip_make_skb+0x228/0x2a0 net/ipv4/ip_output.c:1626 udp_sendmsg+0x1df3/0x27a0 net/ipv4/udp.c:1176 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:814 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x32f/0x810 net/socket.c:2352 ___sys_sendmsg+0x100/0x170 net/socket.c:2406 __sys_sendmmsg+0x195/0x480 net/socket.c:2496 __do_sys_sendmmsg net/socket.c:2525 [inline] __se_sys_sendmmsg net/socket.c:2522 [inline] __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2522 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 15010: save_stack+0x1b/0x40 mm/kasan/common.c:48 set_track mm/kasan/common.c:56 [inline] kasan_set_free_info mm/kasan/common.c:316 [inline] __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:455 __cache_free mm/slab.c:3426 [inline] kfree+0x109/0x2b0 mm/slab.c:3757 skb_free_head+0x8b/0xa0 net/core/skbuff.c:590 skb_release_data+0x617/0x8a0 net/core/skbuff.c:610 skb_release_all+0x46/0x60 net/core/skbuff.c:664 __kfree_skb net/core/skbuff.c:678 [inline] kfree_skb net/core/skbuff.c:696 [inline] kfree_skb+0xfa/0x400 net/core/skbuff.c:690 kfree_skb_list+0x3f/0x60 net/core/skbuff.c:705 __dev_xmit_skb net/core/dev.c:3790 [inline] __dev_queue_xmit+0x20f3/0x2f90 net/core/dev.c:4089 neigh_hh_output include/net/neighbour.h:499 [inline] neigh_output include/net/neighbour.h:508 [inline] ip_finish_output2+0x15a4/0x22e0 net/ipv4/ip_output.c:228 __ip_finish_output net/ipv4/ip_output.c:306 [inline] __ip_finish_output+0x5f3/0xbc0 net/ipv4/ip_output.c:288 ip_finish_output+0x34/0x1f0 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:296 [inline] ip_mc_output+0x266/0xeb0 net/ipv4/ip_output.c:415 dst_output include/net/dst.h:435 [inline] ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:125 ip_send_skb+0x3e/0xe0 net/ipv4/ip_output.c:1560 udp_send_skb.isra.0+0x6cb/0x11c0 net/ipv4/udp.c:894 udp_sendmsg+0x1e40/0x27a0 net/ipv4/udp.c:1181 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:814 sock_sendmsg_nosec net/socket.c:652 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:672 ____sys_sendmsg+0x32f/0x810 net/socket.c:2352 ___sys_sendmsg+0x100/0x170 net/socket.c:2406 __sys_sendmmsg+0x195/0x480 net/socket.c:2496 __do_sys_sendmmsg net/socket.c:2525 [inline] __se_sys_sendmmsg net/socket.c:2522 [inline] __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2522 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The buggy address belongs to the object at ffff8880a869c800 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 262 bytes inside of 512-byte region [ffff8880a869c800, ffff8880a869ca00) The buggy address belongs to the page: page:ffffea0002a1a700 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff8880a869c000 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea00025e8b48 ffffea0002a46f88 ffff8880aa000a80 raw: ffff8880a869c000 ffff8880a869c000 0000000100000002 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a869c800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a869c880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8880a869c900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a869c980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a869ca00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================