================================================================== BUG: KASAN: use-after-free in __fb_pad_aligned_buffer include/linux/fb.h:663 [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+0xb3a/0xcd0 drivers/video/fbdev/core/bitblit.c:185 Read of size 1 at addr ffff8880a18dfcb0 by task syz-executor.3/28047 CPU: 0 PID: 28047 Comm: syz-executor.3 Not tainted 4.14.177-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x13e/0x194 lib/dump_stack.c:58 print_address_description.cold+0x7c/0x1e2 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold+0xa9/0x2ae mm/kasan/report.c:393 __fb_pad_aligned_buffer include/linux/fb.h:663 [inline] bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline] bit_putcs+0xb3a/0xcd0 drivers/video/fbdev/core/bitblit.c:185 fbcon_putcs+0x3c6/0x490 drivers/video/fbdev/core/fbcon.c:1301 do_update_region+0x282/0x5b0 drivers/tty/vt/vt.c:363 update_region drivers/tty/vt/vt.c:391 [inline] update_region+0xdd/0x130 drivers/tty/vt/vt.c:385 vcs_write+0x30d/0xa80 drivers/tty/vt/vc_screen.c:549 do_loop_readv_writev fs/read_write.c:698 [inline] do_loop_readv_writev fs/read_write.c:682 [inline] do_iter_write fs/read_write.c:956 [inline] do_iter_write+0x3d9/0x550 fs/read_write.c:935 vfs_writev+0x170/0x2a0 fs/read_write.c:999 do_writev+0xfc/0x2c0 fs/read_write.c:1034 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x45c829 RSP: 002b:00007f66cbb6bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 000000000050d140 RCX: 000000000045c829 RDX: 0000000000000003 RSI: 0000000020000380 RDI: 0000000000000003 RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000d18 R14: 00000000004cb1f4 R15: 00007f66cbb6c6d4 Allocated by task 25932: save_stack+0x32/0xa0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc mm/kasan/kasan.c:551 [inline] kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:529 __do_kmalloc_node mm/slab.c:3682 [inline] __kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3696 __kmalloc_reserve.isra.0+0x35/0xd0 net/core/skbuff.c:137 __alloc_skb+0xca/0x4c0 net/core/skbuff.c:205 alloc_skb include/linux/skbuff.h:980 [inline] alloc_skb_with_frags+0x85/0x4f0 net/core/skbuff.c:5228 sock_alloc_send_pskb+0x586/0x6d0 net/core/sock.c:2081 __ip_append_data.isra.0+0x11d4/0x2030 net/ipv4/ip_output.c:972 ip_make_skb+0x169/0x1b0 net/ipv4/ip_output.c:1489 udp_sendmsg+0x152e/0x1b70 net/ipv4/udp.c:1052 inet_sendmsg+0x116/0x4d0 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xc5/0x100 net/socket.c:656 ___sys_sendmsg+0x349/0x840 net/socket.c:2062 __sys_sendmmsg+0x129/0x330 net/socket.c:2152 SYSC_sendmmsg net/socket.c:2183 [inline] SyS_sendmmsg+0x2f/0x50 net/socket.c:2178 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 Freed by task 25932: save_stack+0x32/0xa0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcb/0x260 mm/slab.c:3815 skb_free_head+0x83/0xa0 net/core/skbuff.c:554 skb_release_data+0x528/0x7b0 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+0xae/0x340 net/core/skbuff.c:663 __udp4_lib_rcv+0x1bfa/0x2820 net/ipv4/udp.c:2179 ip_local_deliver_finish+0x245/0xaa0 net/ipv4/ip_input.c:216 NF_HOOK include/linux/netfilter.h:250 [inline] NF_HOOK include/linux/netfilter.h:244 [inline] ip_local_deliver+0x1a6/0x450 net/ipv4/ip_input.c:257 dst_input include/net/dst.h:468 [inline] ip_rcv_finish+0x79b/0x1a10 net/ipv4/ip_input.c:396 NF_HOOK include/linux/netfilter.h:250 [inline] NF_HOOK include/linux/netfilter.h:244 [inline] ip_rcv+0x9d8/0xfec net/ipv4/ip_input.c:493 __netif_receive_skb_core+0x1e50/0x2c00 net/core/dev.c:4478 __netif_receive_skb+0x27/0x1a0 net/core/dev.c:4516 process_backlog+0x214/0x750 net/core/dev.c:5198 napi_poll net/core/dev.c:5599 [inline] net_rx_action+0x456/0xe90 net/core/dev.c:5665 __do_softirq+0x254/0x9bf kernel/softirq.c:288 The buggy address belongs to the object at ffff8880a18dfc80 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 48 bytes inside of 512-byte region [ffff8880a18dfc80, ffff8880a18dfe80) The buggy address belongs to the page: page:ffffea00028637c0 count:1 mapcount:0 mapping:ffff8880a18df000 index:0xffff8880a18df000 flags: 0xfffe0000000100(slab) raw: 00fffe0000000100 ffff8880a18df000 ffff8880a18df000 0000000100000002 raw: ffffea00029493e0 ffffea00021cc660 ffff88812fe54940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880a18dfb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a18dfc00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880a18dfc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880a18dfd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880a18dfd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================