KASAN: use-after-free Read in sctp_sock

KASAN: use-after-free Read in sctp_sock_dump
Status: upstream: reported syz repro on 2020/02/10 11:26
Reported-by: syzbot+5992f5ac04ca989e81b8@syzkaller.appspotmail.com
First crash: 657d, last: 66d

Fix bisection: failed (bisect log)
similar bugs (1):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KASAN: use-after-free Read in sctp_sock_dump	syz	done	error	7	607d	762d	0/22	upstream: reported syz repro on 2019/10/28 15:32
Sample crash report:
==================================================================
BUG: KASAN: use-after-free in sctp_sock_dump+0xaa3/0xb20 net/sctp/diag.c:326
Read of size 8 at addr ffff888092656320 by task syz-executor.0/4571

CPU: 0 PID: 4571 Comm: syz-executor.0 Not tainted 4.19.102-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+0x197/0x210 lib/dump_stack.c:118
 print_address_description.cold+0x7c/0x20d 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+0x8c/0x2ba mm/kasan/report.c:396
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 sctp_sock_dump+0xaa3/0xb20 net/sctp/diag.c:326
 sctp_for_each_transport+0x2b4/0x350 net/sctp/socket.c:5062
 sctp_diag_dump+0x33e/0x450 net/sctp/diag.c:528
 __inet_diag_dump+0x9e/0x130 net/ipv4/inet_diag.c:1060
 inet_diag_dump+0x9b/0x110 net/ipv4/inet_diag.c:1076
 netlink_dump+0x427/0xbb0 net/netlink/af_netlink.c:2233
 __netlink_dump_start+0x50d/0x710 net/netlink/af_netlink.c:2329
 netlink_dump_start include/linux/netlink.h:213 [inline]
 inet_diag_handler_cmd+0x262/0x320 net/ipv4/inet_diag.c:1181
 __sock_diag_cmd net/core/sock_diag.c:232 [inline]
 sock_diag_rcv_msg+0x319/0x410 net/core/sock_diag.c:263
 netlink_rcv_skb+0x17d/0x460 net/netlink/af_netlink.c:2454
 sock_diag_rcv+0x2b/0x40 net/core/sock_diag.c:274
 netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
 netlink_unicast+0x53a/0x730 net/netlink/af_netlink.c:1343
 netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1908
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:632
 sock_write_iter+0x2cb/0x400 net/socket.c:901
 call_write_iter include/linux/fs.h:1820 [inline]
 do_iter_readv_writev+0x558/0x830 fs/read_write.c:681
 do_iter_write fs/read_write.c:960 [inline]
 do_iter_write+0x184/0x5f0 fs/read_write.c:941
 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1005
 do_writev+0x15e/0x370 fs/read_write.c:1040
 __do_sys_writev fs/read_write.c:1113 [inline]
 __se_sys_writev fs/read_write.c:1110 [inline]
 __x64_sys_writev+0x75/0xb0 fs/read_write.c:1110
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45b399
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:00007fe2f4277c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fe2f42786d4 RCX: 000000000045b399
RDX: 0000000000000001 RSI: 0000000020000000 RDI: 000000000000000c
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000cdd R14: 00000000004c9cac R15: 000000000075c07c

Allocated by task 4570:
 save_stack+0x45/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc mm/kasan/kasan.c:553 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531
 kmem_cache_alloc_trace+0x152/0x760 mm/slab.c:3625
 kmalloc include/linux/slab.h:515 [inline]
 kzalloc include/linux/slab.h:709 [inline]
 sctp_endpoint_new+0x79/0xd70 net/sctp/endpointola.c:192
 sctp_init_sock+0xb87/0x1290 net/sctp/socket.c:4747
 inet6_create net/ipv6/af_inet6.c:255 [inline]
 inet6_create+0x9bd/0xf70 net/ipv6/af_inet6.c:110
 __sock_create+0x3d8/0x730 net/socket.c:1276
 sock_create net/socket.c:1316 [inline]
 __sys_socket+0x103/0x220 net/socket.c:1346
 __do_sys_socket net/socket.c:1355 [inline]
 __se_sys_socket net/socket.c:1353 [inline]
 __x64_sys_socket+0x73/0xb0 net/socket.c:1353
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4570:
 save_stack+0x45/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcf/0x220 mm/slab.c:3822
 sctp_endpoint_destroy net/sctp/endpointola.c:282 [inline]
 sctp_endpoint_put+0x239/0x2c0 net/sctp/endpointola.c:298
 sctp_endpoint_free+0x77/0x90 net/sctp/endpointola.c:241
 sctp_destroy_sock+0x9f/0x3e0 net/sctp/socket.c:4800
 sctp_v6_destroy_sock+0x16/0x30 net/sctp/socket.c:8959
 sk_common_release+0x6b/0x330 net/core/sock.c:3067
 sctp_close+0x4e4/0x860 net/sctp/socket.c:1567
 inet_release+0xe0/0x1f0 net/ipv4/af_inet.c:427
 inet6_release+0x53/0x80 net/ipv6/af_inet6.c:472
 __sock_release+0xce/0x2a0 net/socket.c:579
 sock_close+0x1b/0x30 net/socket.c:1140
 __fput+0x2dd/0x8b0 fs/file_table.c:278
 ____fput+0x16/0x20 fs/file_table.c:309
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 get_signal+0x1baa/0x1fc0 kernel/signal.c:2394
 do_signal+0x95/0x1960 arch/x86/kernel/signal.c:821
 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:163
 prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
 do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888092656280
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 160 bytes inside of
 512-byte region [ffff888092656280, ffff888092656480)
The buggy address belongs to the page:
page:ffffea0002499580 count:1 mapcount:0 mapping:ffff88812c31c940 index:0xffff888092656780
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea0002118bc8 ffffea000208e808 ffff88812c31c940
raw: ffff888092656780 ffff888092656000 0000000100000005 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888092656200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888092656280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888092656300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888092656380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888092656400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-linux-4-19	2020/02/10 11:25	linux-4.19.y	b499cf4b3a90	35f5e45e	.config	log	report	syz