Subject: [syzbot] [bpf?] [net?] KASAN: slab-use-after-free Read in sk_filter_trim_cap

From: syzbot <[email-masked]>
Date: Wed, 04 Sep 2024 05:35:21 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    33f339a1ba54 bpf, net: Fix a potential race in do_sock_get..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=13f046fb980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=996585887acdadb3
dashboard link: https://syzkaller.appspot.com/bug?extid=b4bc25bfaad44df51f05
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/05db6c7e2db6/disk-33f339a1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/236ebb3d5e01/vmlinux-33f339a1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/97dd5f4e883e/bzImage-33f339a1.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

==================================================================
BUG: KASAN: slab-use-after-free in sk_filter_trim_cap+0x270/0xa80 net/core/filter.c:155
Read of size 8 at addr ffff888062a0a178 by task syz.3.1323/10208

CPU: 0 UID: 0 PID: 10208 Comm: syz.3.1323 Not tainted 6.11.0-rc5-syzkaller-00191-g33f339a1ba54 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 sk_filter_trim_cap+0x270/0xa80 net/core/filter.c:155
 sk_filter include/linux/filter.h:1052 [inline]
 sock_queue_rcv_skb_reason+0x28/0xf0 net/core/sock.c:521
 sock_queue_rcv_skb include/net/sock.h:2376 [inline]
 mgmt_cmd_status+0x28d/0x4d0 net/bluetooth/mgmt_util.c:156
 cmd_status_rsp net/bluetooth/mgmt.c:1450 [inline]
 cmd_complete_rsp+0xe7/0x150 net/bluetooth/mgmt.c:1465
 mgmt_pending_foreach+0xd1/0x130 net/bluetooth/mgmt_util.c:259
 __mgmt_power_off+0x187/0x420 net/bluetooth/mgmt.c:9469
 hci_dev_close_sync+0x665/0x11a0 net/bluetooth/hci_sync.c:5191
 hci_dev_do_close net/bluetooth/hci_core.c:483 [inline]
 hci_dev_close+0x112/0x210 net/bluetooth/hci_core.c:508
 sock_do_ioctl+0x158/0x460 net/socket.c:1222
 sock_ioctl+0x629/0x8e0 net/socket.c:1341
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4ef0d7cef9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4ef1b48038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4ef0f35f80 RCX: 00007f4ef0d7cef9
RDX: 0000000000000000 RSI: 00000000400448ca RDI: 0000000000000005
RBP: 00007f4ef0def01e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f4ef0f35f80 R15: 00007ffef1e33f48
 </TASK>

Allocated by task 6202:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slub.c:4158 [inline]
 __kmalloc_noprof+0x1fc/0x400 mm/slub.c:4170
 kmalloc_noprof include/linux/slab.h:685 [inline]
 sk_prot_alloc+0xe0/0x210 net/core/sock.c:2096
 sk_alloc+0x38/0x370 net/core/sock.c:2149
 bt_sock_alloc+0x3c/0x340 net/bluetooth/af_bluetooth.c:148
 hci_sock_create+0xa1/0x190 net/bluetooth/hci_sock.c:2202
 bt_sock_create+0x161/0x230 net/bluetooth/af_bluetooth.c:132
 __sock_create+0x490/0x920 net/socket.c:1571
 sock_create net/socket.c:1622 [inline]
 __sys_socket_create net/socket.c:1659 [inline]
 __sys_socket+0x150/0x3c0 net/socket.c:1706
 __do_sys_socket net/socket.c:1720 [inline]
 __se_sys_socket net/socket.c:1718 [inline]
 __x64_sys_socket+0x7a/0x90 net/socket.c:1718
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 10210:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
 poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2252 [inline]
 slab_free mm/slub.c:4473 [inline]
 kfree+0x149/0x360 mm/slub.c:4594
 sk_prot_free net/core/sock.c:2132 [inline]
 __sk_destruct+0x479/0x5f0 net/core/sock.c:2224
 sock_put include/net/sock.h:1884 [inline]
 mgmt_pending_free net/bluetooth/mgmt_util.c:307 [inline]
 mgmt_pending_remove+0x13e/0x1a0 net/bluetooth/mgmt_util.c:315
 mgmt_pending_foreach+0xd1/0x130 net/bluetooth/mgmt_util.c:259
 mgmt_index_removed+0xe6/0x340 net/bluetooth/mgmt.c:9402
 hci_sock_bind+0xcce/0x1150 net/bluetooth/hci_sock.c:1307
 __sys_bind_socket net/socket.c:1833 [inline]
 __sys_bind+0x23d/0x2f0 net/socket.c:1857
 __do_sys_bind net/socket.c:1865 [inline]
 __se_sys_bind net/socket.c:1863 [inline]
 __x64_sys_bind+0x7a/0x90 net/socket.c:1863
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888062a0a000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 376 bytes inside of
 freed 2048-byte region [ffff888062a0a000, ffff888062a0a800)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x62a08
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xfdffffff(slab)
raw: 00fff00000000040 ffff88801ac42000 ffffea0000a95600 dead000000000002
raw: 0000000000000000 0000000000080008 00000001fdffffff 0000000000000000
head: 00fff00000000040 ffff88801ac42000 ffffea0000a95600 dead000000000002
head: 0000000000000000 0000000000080008 00000001fdffffff 0000000000000000
head: 00fff00000000003 ffffea00018a8201 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5235, tgid 5235 (syz-executor), ts 58768438859, free_ts 15148990809
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1493
 prep_new_page mm/page_alloc.c:1501 [inline]
 get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3439
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4695
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x5f/0x120 mm/slub.c:2321
 allocate_slab+0x5a/0x2f0 mm/slub.c:2484
 new_slab mm/slub.c:2537 [inline]
 ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3723
 __slab_alloc+0x58/0xa0 mm/slub.c:3813
 __slab_alloc_node mm/slub.c:3866 [inline]
 slab_alloc_node mm/slub.c:4025 [inline]
 __do_kmalloc_node mm/slub.c:4157 [inline]
 __kmalloc_node_track_caller_noprof+0x281/0x440 mm/slub.c:4177
 kmalloc_reserve+0x111/0x2a0 net/core/skbuff.c:605
 __alloc_skb+0x1f3/0x440 net/core/skbuff.c:674
 alloc_skb include/linux/skbuff.h:1320 [inline]
 nlmsg_new include/net/netlink.h:1015 [inline]
 inet6_ifinfo_notify+0x72/0x120 net/ipv6/addrconf.c:6162
 addrconf_notify+0xc6b/0x1020 net/ipv6/addrconf.c:3763
 notifier_call_chain+0x19f/0x3e0 kernel/notifier.c:93
 __dev_notify_flags+0x207/0x400
 dev_change_flags+0xf0/0x1a0 net/core/dev.c:8915
 do_setlink+0xcd0/0x41f0 net/core/rtnetlink.c:2900
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1094 [inline]
 free_unref_page+0xd22/0xea0 mm/page_alloc.c:2612
 free_contig_range+0x9e/0x160 mm/page_alloc.c:6660
 destroy_args+0x8a/0x890 mm/debug_vm_pgtable.c:1017
 debug_vm_pgtable+0x4be/0x550 mm/debug_vm_pgtable.c:1397
 do_one_initcall+0x248/0x880 init/main.c:1267
 do_initcall_level+0x157/0x210 init/main.c:1329
 do_initcalls+0x3f/0x80 init/main.c:1345
 kernel_init_freeable+0x435/0x5d0 init/main.c:1578
 kernel_init+0x1d/0x2b0 init/main.c:1467
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
 ffff888062a0a000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888062a0a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888062a0a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff888062a0a180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888062a0a200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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