KASAN: use-after-free Read in inet_diag_bc_sk

From: syzbot
Date: Fri May 01 2020 - 07:09:22 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 37ecb5b8 hinic: Use kmemdup instead of kzalloc and memcpy
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=141e54bc100000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1494ce3fbc02154
dashboard link: https://syzkaller.appspot.com/bug?extid=13bef047dbfffa5cd1af
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12296e60100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=150c6f02100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+13bef047dbfffa5cd1af@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in cgroup_id include/linux/cgroup.h:312 [inline]
BUG: KASAN: use-after-free in inet_diag_bc_sk+0xb6e/0xc70 net/ipv4/inet_diag.c:749
Read of size 8 at addr ffff88821b2c9f08 by task syz-executor674/7229

CPU: 1 PID: 7229 Comm: syz-executor674 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
cgroup_id include/linux/cgroup.h:312 [inline]
inet_diag_bc_sk+0xb6e/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: 0033:0x443d69
Code: e8 8c 07 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 3b 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffea5636068 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000443d69
RDX: 0000000000000001 RSI: 0000000020000200 RDI: 0000000000000006
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000e475
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 1:
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
kmem_cache_zalloc include/linux/slab.h:659 [inline]
__kernfs_new_node+0xd4/0x690 fs/kernfs/dir.c:627
kernfs_new_node+0x93/0x120 fs/kernfs/dir.c:689
__kernfs_create_file+0x51/0x350 fs/kernfs/file.c:1001
sysfs_add_file_mode_ns+0x224/0x520 fs/sysfs/file.c:305
create_files fs/sysfs/group.c:64 [inline]
internal_create_group+0x327/0xba0 fs/sysfs/group.c:149
kernel_add_sysfs_param kernel/params.c:795 [inline]
param_sysfs_builtin kernel/params.c:832 [inline]
param_sysfs_init+0x3a0/0x430 kernel/params.c:953
do_one_initcall+0x10a/0x7d0 init/main.c:1157
do_initcall_level init/main.c:1230 [inline]
do_initcalls init/main.c:1246 [inline]
do_basic_setup init/main.c:1266 [inline]
kernel_init_freeable+0x501/0x5ae init/main.c:1450
kernel_init+0xd/0x1bb init/main.c:1357
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 1:
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
kernfs_put fs/kernfs/dir.c:537 [inline]
kernfs_put+0x2f9/0x570 fs/kernfs/dir.c:506
__kernfs_remove fs/kernfs/dir.c:1344 [inline]
__kernfs_remove+0x690/0x950 fs/kernfs/dir.c:1282
kernfs_remove_by_name_ns+0x51/0xb0 fs/kernfs/dir.c:1516
kernfs_remove_by_name include/linux/kernfs.h:593 [inline]
remove_files.isra.0+0x76/0x190 fs/sysfs/group.c:28
sysfs_remove_group+0xb3/0x1b0 fs/sysfs/group.c:289
kernel_add_sysfs_param kernel/params.c:790 [inline]
param_sysfs_builtin kernel/params.c:832 [inline]
param_sysfs_init+0x333/0x430 kernel/params.c:953
do_one_initcall+0x10a/0x7d0 init/main.c:1157
do_initcall_level init/main.c:1230 [inline]
do_initcalls init/main.c:1246 [inline]
do_basic_setup init/main.c:1266 [inline]
kernel_init_freeable+0x501/0x5ae init/main.c:1450
kernel_init+0xd/0x1bb init/main.c:1357
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

The buggy address belongs to the object at ffff88821b2c9e80
which belongs to the cache kernfs_node_cache of size 168
The buggy address is located 136 bytes inside of
168-byte region [ffff88821b2c9e80, ffff88821b2c9f28)
The buggy address belongs to the page:
page:ffffea00086cb240 refcount:1 mapcount:0 mapping:00000000c46c458d index:0xffff88821b2c9000
flags: 0x57ffe0000000200(slab)
raw: 057ffe0000000200 ffffea00086cb288 ffffea00086cb148 ffff88821bc508c0
raw: ffff88821b2c9000 ffff88821b2c9000 0000000100000009 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88821b2c9e00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
ffff88821b2c9e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88821b2c9f00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
^
ffff88821b2c9f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88821b2ca000: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================

---
This bug is generated by a bot. It may contain errors.
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Next message: syzbot: "KASAN: slab-out-of-bounds Read in inet_diag_bc_sk"
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