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KASAN: use-after-free Read in inet_diag_bc_sk

Status: fixed on 2020/07/17 17:58
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+13bef047dbfffa5cd1af@syzkaller.appspotmail.com
Fix commit: ee1bd483cc06 inet_diag: bc: read cgroup id only for full sockets
First crash: 1456d, last: 1454d
Cause bisection: introduced by (bisect log) :
commit b1f3e43dbfacfcd95296b0f80f84b186add9ef54
Author: Dmitry Yakunin <zeil@yandex-team.ru>
Date: Thu Apr 30 15:51:15 2020 +0000

  inet_diag: add support for cgroup filter

Crash: KASAN: use-after-free Read in inet_diag_bc_sk (log)
Repro: C syz .config
  
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH net-next] inet_diag: bc: read cgroup id only for full sockets 2 (2) 2020/05/02 23:43
KASAN: use-after-free Read in inet_diag_bc_sk 0 (2) 2020/05/01 14:49

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:199 [inline]
BUG: KASAN: use-after-free in sock_cgroup_ptr include/linux/cgroup.h:836 [inline]
BUG: KASAN: use-after-free in inet_diag_bc_sk+0xb64/0xc70 net/ipv4/inet_diag.c:749
Read of size 8 at addr ffff8880995d9260 by task syz-executor478/7040

CPU: 1 PID: 7040 Comm: syz-executor478 Not tainted 5.7.0-rc2-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+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:382
 __kasan_report.cold+0x35/0x4d mm/kasan/report.c:511
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 __read_once_size include/linux/compiler.h:199 [inline]
 sock_cgroup_ptr include/linux/cgroup.h:836 [inline]
 inet_diag_bc_sk+0xb64/0xc70 net/ipv4/inet_diag.c:749
 inet_diag_dump_icsk+0xbe4/0x1306 net/ipv4/inet_diag.c:1061
 __inet_diag_dump+0x8d/0x240 net/ipv4/inet_diag.c:1113
 netlink_dump+0x50b/0xf50 net/netlink/af_netlink.c:2245
 __netlink_dump_start+0x63f/0x910 net/netlink/af_netlink.c:2353
 netlink_dump_start include/linux/netlink.h:246 [inline]
 inet_diag_handler_cmd+0x263/0x2c0 net/ipv4/inet_diag.c:1278
 __sock_diag_cmd net/core/sock_diag.c:233 [inline]
 sock_diag_rcv_msg+0x2fe/0x3e0 net/core/sock_diag.c:264
 netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2469
 sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:275
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 sock_write_iter+0x289/0x3c0 net/socket.c:1004
 call_write_iter include/linux/fs.h:1907 [inline]
 do_iter_readv_writev+0x5a8/0x850 fs/read_write.c:694
 do_iter_write fs/read_write.c:999 [inline]
 do_iter_write+0x18b/0x600 fs/read_write.c:980
 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1072
 do_writev+0x27f/0x300 fs/read_write.c:1115
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x4403e9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffcdd5db058 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004403e9
RDX: 0000000000000001 RSI: 0000000020000140 RDI: 0000000000000005
RBP: 00000000006ca018 R08: 000000000000001c R09: 00000000004002c8
R10: 000000000000001c R11: 0000000000000246 R12: 0000000000401c70
R13: 0000000000401d00 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 5017:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 __kasan_kmalloc mm/kasan/common.c:495 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:468
 slab_post_alloc_hook mm/slab.h:586 [inline]
 slab_alloc mm/slab.c:3320 [inline]
 kmem_cache_alloc+0x11b/0x740 mm/slab.c:3484
 prepare_creds+0x39/0x6b0 kernel/cred.c:258
 do_faccessat+0x94/0x7a0 fs/open.c:360
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Freed by task 5017:
 save_stack+0x1b/0x40 mm/kasan/common.c:49
 set_track mm/kasan/common.c:57 [inline]
 kasan_set_free_info mm/kasan/common.c:317 [inline]
 __kasan_slab_free+0xf7/0x140 mm/kasan/common.c:456
 __cache_free mm/slab.c:3426 [inline]
 kmem_cache_free+0x7f/0x320 mm/slab.c:3694
 __put_cred+0x1de/0x250 kernel/cred.c:148
 put_cred include/linux/cred.h:287 [inline]
 do_faccessat+0x64d/0x7a0 fs/open.c:439
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

The buggy address belongs to the object at ffff8880995d9200
 which belongs to the cache cred_jar of size 184
The buggy address is located 96 bytes inside of
 184-byte region [ffff8880995d9200, ffff8880995d92b8)
The buggy address belongs to the page:
page:ffffea0002657640 refcount:1 mapcount:0 mapping:00000000b1d6d84a index:0xffff8880995d9e00
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00029cd2c8 ffffea00026c94c8 ffff8880aa1eba80
raw: ffff8880995d9e00 ffff8880995d9000 0000000100000005 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880995d9100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880995d9180: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc
>ffff8880995d9200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff8880995d9280: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc
 ffff8880995d9300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (30):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2020/05/01 15:04 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report syz C ci-upstream-net-kasan-gce
2020/05/01 11:48 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report syz C ci-upstream-net-kasan-gce
2020/05/01 09:31 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report syz C ci-upstream-net-kasan-gce
2020/05/03 12:12 net-next-old 115506fea499 5457883a .config console log report ci-upstream-net-kasan-gce
2020/05/03 10:30 net-next-old 115506fea499 5457883a .config console log report ci-upstream-net-kasan-gce
2020/05/03 10:24 net-next-old 115506fea499 5457883a .config console log report ci-upstream-net-kasan-gce
2020/05/03 06:42 net-next-old 115506fea499 5457883a .config console log report ci-upstream-net-kasan-gce
2020/05/02 22:41 net-next-old bf2320a60e68 58da4c35 .config console log report ci-upstream-net-kasan-gce
2020/05/02 22:20 net-next-old bf2320a60e68 58da4c35 .config console log report ci-upstream-net-kasan-gce
2020/05/02 21:49 net-next-old bf2320a60e68 58da4c35 .config console log report ci-upstream-net-kasan-gce
2020/05/02 21:27 net-next-old bf2320a60e68 58da4c35 .config console log report ci-upstream-net-kasan-gce
2020/05/02 17:15 net-next-old bf2320a60e68 58da4c35 .config console log report ci-upstream-net-kasan-gce
2020/05/02 16:58 net-next-old bf2320a60e68 58da4c35 .config console log report ci-upstream-net-kasan-gce
2020/05/02 15:23 net-next-old bf2320a60e68 58da4c35 .config console log report ci-upstream-net-kasan-gce
2020/05/02 12:30 net-next-old bf2320a60e68 58da4c35 .config console log report ci-upstream-net-kasan-gce
2020/05/02 11:22 net-next-old bf2320a60e68 58da4c35 .config console log report ci-upstream-net-kasan-gce
2020/05/02 08:19 net-next-old 4b4976a6fec5 bc734e7a .config console log report ci-upstream-net-kasan-gce
2020/05/02 05:52 net-next-old 4b4976a6fec5 bc734e7a .config console log report ci-upstream-net-kasan-gce
2020/05/02 05:35 net-next-old 4b4976a6fec5 bc734e7a .config console log report ci-upstream-net-kasan-gce
2020/05/02 05:00 net-next-old 4b4976a6fec5 bc734e7a .config console log report ci-upstream-net-kasan-gce
2020/05/02 03:36 net-next-old 4b4976a6fec5 bc734e7a .config console log report ci-upstream-net-kasan-gce
2020/05/01 18:29 net-next-old 37ecb5b8b8cd bc734e7a .config console log report ci-upstream-net-kasan-gce
2020/05/01 15:38 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report ci-upstream-net-kasan-gce
2020/05/01 14:57 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report ci-upstream-net-kasan-gce
2020/05/01 14:40 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report ci-upstream-net-kasan-gce
2020/05/01 14:05 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report ci-upstream-net-kasan-gce
2020/05/01 13:41 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report ci-upstream-net-kasan-gce
2020/05/01 12:53 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report ci-upstream-net-kasan-gce
2020/05/01 09:53 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report ci-upstream-net-kasan-gce
2020/05/01 06:52 net-next-old 37ecb5b8b8cd a4d01b80 .config console log report ci-upstream-net-kasan-gce
* Struck through repros no longer work on HEAD.