syzbot

==================================================================
BUG: KASAN: use-after-free in rxrpc_new_skb+0x3eb/0x450 net/rxrpc/skbuff.c:26
Read of size 1 at addr ffff888036bea92d by task syz-executor.2/20246

CPU: 0 PID: 20246 Comm: syz-executor.2 Not tainted 5.3.0-rc8 #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+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0xd4/0x306 mm/kasan/report.c:351
 __kasan_report.cold+0x1b/0x36 mm/kasan/report.c:482
 kasan_report+0x12/0x17 mm/kasan/common.c:618
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/generic_report.c:129
 rxrpc_new_skb+0x3eb/0x450 net/rxrpc/skbuff.c:26
 rxrpc_input_packet+0x890/0x586b net/rxrpc/input.c:1265
 udp_queue_rcv_one_skb+0xaf0/0x17d0 net/ipv4/udp.c:1996
 udp_queue_rcv_skb+0x128/0x790 net/ipv4/udp.c:2070
 udp_unicast_rcv_skb.isra.0+0xb9/0x360 net/ipv4/udp.c:2229
 __udp4_lib_rcv+0x701/0x2ca0 net/ipv4/udp.c:2285
 udp_rcv+0x22/0x30 net/ipv4/udp.c:2466
 ip_protocol_deliver_rcu+0x5a/0x8b0 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x23b/0x390 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_local_deliver+0x1e9/0x520 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x1d9/0x2e0 net/ipv4/ip_input.c:413
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_rcv+0xe8/0x3f0 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core+0x113/0x1a0 net/core/dev.c:5004
 __netif_receive_skb+0x2c/0x1d0 net/core/dev.c:5118
 netif_receive_skb_internal+0x108/0x390 net/core/dev.c:5208
 netif_receive_skb+0x87/0x600 net/core/dev.c:5267
 tun_rx_batched.isra.0+0x4f7/0x840 drivers/net/tun.c:1551
 tun_get_user+0x148d/0x3fa0 drivers/net/tun.c:1991
 tun_chr_write_iter+0xbd/0x156 drivers/net/tun.c:2020
 call_write_iter include/linux/fs.h:1870 [inline]
 do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x184/0x610 fs/read_write.c:951
 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1015
 do_writev+0x15b/0x330 fs/read_write.c:1058
 __do_sys_writev fs/read_write.c:1131 [inline]
 __se_sys_writev fs/read_write.c:1128 [inline]
 __x64_sys_writev+0x75/0xb0 fs/read_write.c:1128
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4597a1
Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 b9 fb ff c3 48 83 ec 08 e8 fa 2c 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 43 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f98b6d13ba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0000000000000046 RCX: 00000000004597a1
RDX: 0000000000000001 RSI: 00007f98b6d13c00 RDI: 00000000000000f0
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f98b6d146d4
R13: 00000000004c881c R14: 00000000004df6c0 R15: 00000000ffffffff

Allocated by task 20246:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_kmalloc mm/kasan/common.c:493 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:466
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:501
 slab_post_alloc_hook mm/slab.h:520 [inline]
 slab_alloc mm/slab.c:3319 [inline]
 kmem_cache_alloc+0x121/0x710 mm/slab.c:3483
 __build_skb+0x26/0x70 net/core/skbuff.c:310
 build_skb+0x21/0x190 net/core/skbuff.c:326
 __tun_build_skb drivers/net/tun.c:1606 [inline]
 tun_build_skb.isra.0+0xbe6/0x1390 drivers/net/tun.c:1691
 tun_get_user+0x8d3/0x3fa0 drivers/net/tun.c:1816
 tun_chr_write_iter+0xbd/0x156 drivers/net/tun.c:2020
 call_write_iter include/linux/fs.h:1870 [inline]
 do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x184/0x610 fs/read_write.c:951
 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1015
 do_writev+0x15b/0x330 fs/read_write.c:1058
 __do_sys_writev fs/read_write.c:1131 [inline]
 __se_sys_writev fs/read_write.c:1128 [inline]
 __x64_sys_writev+0x75/0xb0 fs/read_write.c:1128
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 20246:
 save_stack+0x23/0x90 mm/kasan/common.c:69
 set_track mm/kasan/common.c:77 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:455
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:463
 __cache_free mm/slab.c:3425 [inline]
 kmem_cache_free+0x86/0x320 mm/slab.c:3693
 kfree_skbmem net/core/skbuff.c:623 [inline]
 kfree_skbmem+0xc5/0x150 net/core/skbuff.c:617
 __kfree_skb net/core/skbuff.c:680 [inline]
 consume_skb net/core/skbuff.c:838 [inline]
 consume_skb+0x103/0x3b0 net/core/skbuff.c:832
 skb_unshare include/linux/skbuff.h:1715 [inline]
 rxrpc_input_packet+0x869/0x586b net/rxrpc/input.c:1257
 udp_queue_rcv_one_skb+0xaf0/0x17d0 net/ipv4/udp.c:1996
 udp_queue_rcv_skb+0x128/0x790 net/ipv4/udp.c:2070
 udp_unicast_rcv_skb.isra.0+0xb9/0x360 net/ipv4/udp.c:2229
 __udp4_lib_rcv+0x701/0x2ca0 net/ipv4/udp.c:2285
 udp_rcv+0x22/0x30 net/ipv4/udp.c:2466
 ip_protocol_deliver_rcu+0x5a/0x8b0 net/ipv4/ip_input.c:204
 ip_local_deliver_finish+0x23b/0x390 net/ipv4/ip_input.c:231
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_local_deliver+0x1e9/0x520 net/ipv4/ip_input.c:252
 dst_input include/net/dst.h:442 [inline]
 ip_rcv_finish+0x1d9/0x2e0 net/ipv4/ip_input.c:413
 NF_HOOK include/linux/netfilter.h:305 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_rcv+0xe8/0x3f0 net/ipv4/ip_input.c:523
 __netif_receive_skb_one_core+0x113/0x1a0 net/core/dev.c:5004
 __netif_receive_skb+0x2c/0x1d0 net/core/dev.c:5118
 netif_receive_skb_internal+0x108/0x390 net/core/dev.c:5208
 netif_receive_skb+0x87/0x600 net/core/dev.c:5267
 tun_rx_batched.isra.0+0x4f7/0x840 drivers/net/tun.c:1551
 tun_get_user+0x148d/0x3fa0 drivers/net/tun.c:1991
 tun_chr_write_iter+0xbd/0x156 drivers/net/tun.c:2020
 call_write_iter include/linux/fs.h:1870 [inline]
 do_iter_readv_writev+0x5f8/0x8f0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x184/0x610 fs/read_write.c:951
 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1015
 do_writev+0x15b/0x330 fs/read_write.c:1058
 __do_sys_writev fs/read_write.c:1131 [inline]
 __se_sys_writev fs/read_write.c:1128 [inline]
 __x64_sys_writev+0x75/0xb0 fs/read_write.c:1128
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888036bea900
 which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 45 bytes inside of
 224-byte region [ffff888036bea900, ffff888036bea9e0)
The buggy address belongs to the page:
page:ffffea0000dafa80 refcount:1 mapcount:0 mapping:ffff8880a99f4a80 index:0xffff888036bea040
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0001a2d988 ffffea0002725408 ffff8880a99f4a80
raw: ffff888036bea040 ffff888036bea040 0000000100000008 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888036bea800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888036bea880: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888036bea900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff888036bea980: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888036beaa00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================