bisecting fixing commit since ef244c3088856cf048c77231653b4c92a7b2213c
building syzkaller on b35fad31e9c2d4a970d051deff80ec7cc4c3e459
testing commit ef244c3088856cf048c77231653b4c92a7b2213c with gcc (GCC) 8.1.0
kernel signature: 0b8b5a4043a9180dc66663efcc48128b3664a1ebb8c41e53af5b2ceaedf9a2d0
all runs: crashed: KASAN: use-after-free Read in ccid2_hc_tx_packet_recv
testing current HEAD dda0e2920330128e0dbdeb11c8f25031aa40b11c
testing commit dda0e2920330128e0dbdeb11c8f25031aa40b11c with gcc (GCC) 8.1.0
kernel signature: 8278e97dd0ee141ae3296a7f2608d496dd7e180ccee12cdb5be61fcc781f6137
all runs: crashed: KASAN: use-after-free Read in ccid2_hc_tx_packet_recv
revisions tested: 2, total time: 24m29.816427806s (build: 17m30.366578123s, test: 5m56.615974003s)
the crash still happens on HEAD
commit msg: Linux 4.19.114
crash: KASAN: use-after-free Read in ccid2_hc_tx_packet_recv
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x123/0x177 lib/dump_stack.c:118
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold.4+0x5/0x13 lib/fault-inject.c:149
==================================================================
 __should_failslab+0xba/0xf0 mm/failslab.c:32
BUG: KASAN: use-after-free in ccid2_hc_tx_packet_recv+0x1edd/0x21d3 net/dccp/ccids/ccid2.c:600
Read of size 1 at addr ffff888091ad0522 by task syz-executor.5/7294
 should_failslab+0x9/0x14 mm/slab_common.c:1558

 slab_pre_alloc_hook mm/slab.h:424 [inline]
 slab_alloc mm/slab.c:3383 [inline]
 kmem_cache_alloc_trace+0x4b/0x740 mm/slab.c:3623
 kmalloc include/linux/slab.h:515 [inline]
 dccp_ackvec_parsed_add+0x51/0x220 net/dccp/ackvec.c:352
 ccid2_hc_tx_parse_options+0x5b/0x80 net/dccp/ccids/ccid2.c:513
 ccid_hc_tx_parse_options net/dccp/ccid.h:207 [inline]
 dccp_parse_options+0x532/0xf20 net/dccp/options.c:233
 dccp_rcv_established+0x23/0x70 net/dccp/input.c:374
 dccp_v4_do_rcv+0xfa/0x160 net/dccp/ipv4.c:656
 sk_backlog_rcv include/net/sock.h:946 [inline]
 __release_sock+0x107/0x360 net/core/sock.c:2342
 release_sock+0x4f/0x180 net/core/sock.c:2858
 dccp_sendmsg+0x4f6/0xe20 net/dccp/proto.c:818
 inet_sendmsg+0x108/0x440 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xb5/0xf0 net/socket.c:632
 ___sys_sendmsg+0x28e/0x950 net/socket.c:2115
 __sys_sendmmsg+0x160/0x370 net/socket.c:2210
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg net/socket.c:2236 [inline]
 __x64_sys_sendmmsg+0x98/0x100 net/socket.c:2236
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
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:00007f0b1192fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f0b1192fc90 RCX: 000000000045a219
RDX: 04000000000001e6 RSI: 0000000020000c00 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0b119306d4
R13: 00000000004c7fba R14: 00000000004de3e8 R15: 0000000000000006
CPU: 0 PID: 7294 Comm: syz-executor.5 Not tainted 4.19.114-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+0x123/0x177 lib/dump_stack.c:118
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 ccid2_hc_tx_packet_recv+0x1edd/0x21d3 net/dccp/ccids/ccid2.c:600
 ccid_hc_tx_packet_recv net/dccp/ccid.h:192 [inline]
 dccp_deliver_input_to_ccids+0x19f/0x210 net/dccp/input.c:186
 dccp_rcv_established+0x49/0x70 net/dccp/input.c:378
 dccp_v4_do_rcv+0xfa/0x160 net/dccp/ipv4.c:656
 sk_backlog_rcv include/net/sock.h:946 [inline]
 __release_sock+0x107/0x360 net/core/sock.c:2342
 release_sock+0x4f/0x180 net/core/sock.c:2858
 dccp_sendmsg+0x4f6/0xe20 net/dccp/proto.c:818
 inet_sendmsg+0x108/0x440 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xb5/0xf0 net/socket.c:632
 ___sys_sendmsg+0x28e/0x950 net/socket.c:2115
dccp_parse_options: DCCP(00000000433cb479): Option 38 (len=1) error=5
 __sys_sendmmsg+0x160/0x370 net/socket.c:2210
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg net/socket.c:2236 [inline]
 __x64_sys_sendmmsg+0x98/0x100 net/socket.c:2236
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
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:00007ff56a948c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007ff56a948c90 RCX: 000000000045a219
RDX: 04000000000001e6 RSI: 0000000020000c00 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff56a9496d4
R13: 00000000004c7fba R14: 00000000004de3e8 R15: 0000000000000006

CPU: 1 PID: 7316 Comm: syz-executor.1 Not tainted 4.19.114-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Allocated by task 7294:
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x123/0x177 lib/dump_stack.c:118
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold.4+0x5/0x13 lib/fault-inject.c:149
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc_node mm/slab.c:3689 [inline]
 __kmalloc_node_track_caller+0x50/0x70 mm/slab.c:3703
 __kmalloc_reserve.isra.39+0x2c/0xc0 net/core/skbuff.c:137
 __alloc_skb+0xd7/0x580 net/core/skbuff.c:205
 __should_failslab+0xba/0xf0 mm/failslab.c:32
 alloc_skb include/linux/skbuff.h:995 [inline]
 dccp_send_ack+0xb3/0x340 net/dccp/output.c:580
 ccid2_hc_rx_packet_recv+0xf9/0x170 net/dccp/ccids/ccid2.c:779
 should_failslab+0x9/0x14 mm/slab_common.c:1558
 ccid_hc_rx_packet_recv net/dccp/ccid.h:185 [inline]
 dccp_deliver_input_to_ccids+0xc5/0x210 net/dccp/input.c:180
 slab_pre_alloc_hook mm/slab.h:424 [inline]
 slab_alloc mm/slab.c:3383 [inline]
 kmem_cache_alloc_trace+0x4b/0x740 mm/slab.c:3623
 dccp_rcv_established+0x49/0x70 net/dccp/input.c:378
 dccp_v4_do_rcv+0xfa/0x160 net/dccp/ipv4.c:656
 kmalloc include/linux/slab.h:515 [inline]
 dccp_ackvec_parsed_add+0x51/0x220 net/dccp/ackvec.c:352
 sk_backlog_rcv include/net/sock.h:946 [inline]
 __sk_receive_skb+0x2a2/0x9a0 net/core/sock.c:473
 dccp_v4_rcv+0xbcd/0x1bbd net/dccp/ipv4.c:877
 ccid2_hc_tx_parse_options+0x5b/0x80 net/dccp/ccids/ccid2.c:513
 ip_local_deliver_finish+0x235/0x9f0 net/ipv4/ip_input.c:215
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip_local_deliver+0x2f7/0x440 net/ipv4/ip_input.c:256
 ccid_hc_tx_parse_options net/dccp/ccid.h:207 [inline]
 dccp_parse_options+0x532/0xf20 net/dccp/options.c:233
 dst_input include/net/dst.h:453 [inline]
 ip_rcv_finish+0x166/0x270 net/ipv4/ip_input.c:414
 dccp_rcv_established+0x23/0x70 net/dccp/input.c:374
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip_rcv+0xcb/0x2e0 net/ipv4/ip_input.c:524
 dccp_v4_do_rcv+0xfa/0x160 net/dccp/ipv4.c:656
 __netif_receive_skb_one_core+0xe9/0x170 net/core/dev.c:4947
 __netif_receive_skb+0x1f/0x1b0 net/core/dev.c:5059
 sk_backlog_rcv include/net/sock.h:946 [inline]
 __release_sock+0x107/0x360 net/core/sock.c:2342
 process_backlog+0x1ca/0x6d0 net/core/dev.c:5841
 release_sock+0x4f/0x180 net/core/sock.c:2858
 napi_poll net/core/dev.c:6264 [inline]
 net_rx_action+0x470/0xe20 net/core/dev.c:6330
 __do_softirq+0x260/0x92d kernel/softirq.c:292
 dccp_sendmsg+0x4f6/0xe20 net/dccp/proto.c:818

Freed by task 7294:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 inet_sendmsg+0x108/0x440 net/ipv4/af_inet.c:798
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcf/0x220 mm/slab.c:3822
 skb_free_head+0x74/0x90 net/core/skbuff.c:554
 skb_release_data+0x481/0x6c0 net/core/skbuff.c:574
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xb5/0xf0 net/socket.c:632
 skb_release_all+0x3d/0x50 net/core/skbuff.c:631
 ___sys_sendmsg+0x28e/0x950 net/socket.c:2115
 __kfree_skb net/core/skbuff.c:645 [inline]
 kfree_skb+0x97/0x270 net/core/skbuff.c:663
 dccp_v4_do_rcv+0x111/0x160 net/dccp/ipv4.c:691
 sk_backlog_rcv include/net/sock.h:946 [inline]
 __release_sock+0x107/0x360 net/core/sock.c:2342
 release_sock+0x4f/0x180 net/core/sock.c:2858
 dccp_sendmsg+0x4f6/0xe20 net/dccp/proto.c:818
 inet_sendmsg+0x108/0x440 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xb5/0xf0 net/socket.c:632
 ___sys_sendmsg+0x28e/0x950 net/socket.c:2115
 __sys_sendmmsg+0x160/0x370 net/socket.c:2210
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg net/socket.c:2236 [inline]
 __x64_sys_sendmmsg+0x98/0x100 net/socket.c:2236
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

 __sys_sendmmsg+0x160/0x370 net/socket.c:2210
The buggy address belongs to the object at ffff888091ad0080
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 1186 bytes inside of
 2048-byte region [ffff888091ad0080, ffff888091ad0880)
The buggy address belongs to the page:
page:ffffea000246b400 count:1 mapcount:0 mapping:ffff88812c35ec40 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000008100(slab|head)
raw: 01fffc0000008100 ffffea0002532a88 ffffea000246b508 ffff88812c35ec40
raw: 0000000000000000 ffff888091ad0080 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888091ad0400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888091ad0480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888091ad0500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888091ad0580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg net/socket.c:2236 [inline]
 __x64_sys_sendmmsg+0x98/0x100 net/socket.c:2236
 ffff888091ad0600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
==================================================================
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
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:00007ff1d5a2ec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007ff1d5a2ec90 RCX: 000000000045a219
RDX: 04000000000001e6 RSI: 0000000020000c00 RDI: 0000000000000005
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff1d5a2f6d4
R13: 00000000004c7fba R14: 00000000004de3e8 R15: 0000000000000006
CPU: 0 PID: 7313 Comm: syz-executor.4 Tainted: G    B             4.19.114-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+0x123/0x177 lib/dump_stack.c:118
 fail_dump lib/fault-inject.c:51 [inline]
 should_fail.cold.4+0x5/0x13 lib/fault-inject.c:149
 __should_failslab+0xba/0xf0 mm/failslab.c:32
 should_failslab+0x9/0x14 mm/slab_common.c:1558
 slab_pre_alloc_hook mm/slab.h:424 [inline]
 slab_alloc mm/slab.c:3383 [inline]
 kmem_cache_alloc_trace+0x4b/0x740 mm/slab.c:3623
 kmalloc include/linux/slab.h:515 [inline]
 dccp_ackvec_parsed_add+0x51/0x220 net/dccp/ackvec.c:352
 ccid2_hc_tx_parse_options+0x5b/0x80 net/dccp/ccids/ccid2.c:513
 ccid_hc_tx_parse_options net/dccp/ccid.h:207 [inline]
 dccp_parse_options+0x532/0xf20 net/dccp/options.c:233
 dccp_rcv_established+0x23/0x70 net/dccp/input.c:374
 dccp_v4_do_rcv+0xfa/0x160 net/dccp/ipv4.c:656
 sk_backlog_rcv include/net/sock.h:946 [inline]
 __release_sock+0x107/0x360 net/core/sock.c:2342
 release_sock+0x4f/0x180 net/core/sock.c:2858
 dccp_sendmsg+0x4f6/0xe20 net/dccp/proto.c:818
 inet_sendmsg+0x108/0x440 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xb5/0xf0 net/socket.c:632
 ___sys_sendmsg+0x28e/0x950 net/socket.c:2115