Subject: Re: [syzbot] [net?] [nfc?] KASAN: slab-use-after-free Read in nfc_alloc_send_skb

From: syzbot <[email-masked]>
Date: Mon, 13 Nov 2023 05:48:06 -0800

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in nfc_alloc_send_skb

==================================================================
BUG: KASAN: slab-use-after-free in nfc_alloc_send_skb+0x189/0x1c0 net/nfc/core.c:726
Read of size 4 at addr ffff888020c66548 by task syz-executor.0/5482

CPU: 0 PID: 5482 Comm: syz-executor.0 Not tainted 6.7.0-rc1-syzkaller-gb85ea95d0864-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0x163/0x540 mm/kasan/report.c:475
 kasan_report+0x142/0x170 mm/kasan/report.c:588
 nfc_alloc_send_skb+0x189/0x1c0 net/nfc/core.c:726
 nfc_llcp_send_ui_frame+0x2ac/0x670 net/nfc/llcp_commands.c:766
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x592/0x890 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmmsg+0x3b2/0x730 net/socket.c:2724
 __do_sys_sendmmsg net/socket.c:2753 [inline]
 __se_sys_sendmmsg net/socket.c:2750 [inline]
 __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2750
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7fc24e27cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc24efbd0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fc24e39bf80 RCX: 00007fc24e27cae9
RDX: 0000000000000001 RSI: 00000000200013c0 RDI: 0000000000000004
RBP: 00007fc24e2c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fc24e39bf80 R15: 00007ffff6582e38
 </TASK>

Allocated by task 5482:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 nfc_allocate_device+0x12f/0x520 net/nfc/core.c:1065
 nci_allocate_device+0x1e2/0x360 net/nfc/nci/core.c:1179
 virtual_ncidev_open+0x75/0x1b0 drivers/nfc/virtual_ncidev.c:136
 misc_open+0x30b/0x380 drivers/char/misc.c:165
 chrdev_open+0x5ab/0x630 fs/char_dev.c:414
 do_dentry_open+0x8fd/0x1590 fs/open.c:948
 do_open fs/namei.c:3622 [inline]
 path_openat+0x2845/0x3280 fs/namei.c:3779
 do_filp_open+0x234/0x490 fs/namei.c:3809
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
 do_sys_open fs/open.c:1455 [inline]
 __do_sys_openat fs/open.c:1471 [inline]
 __se_sys_openat fs/open.c:1466 [inline]
 __x64_sys_openat+0x247/0x290 fs/open.c:1466
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Freed by task 5481:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1800 [inline]
 slab_free_freelist_hook mm/slub.c:1826 [inline]
 slab_free mm/slub.c:3809 [inline]
 __kmem_cache_free+0x263/0x3a0 mm/slub.c:3822
 device_release+0x95/0x1c0
 kobject_cleanup lib/kobject.c:682 [inline]
 kobject_release lib/kobject.c:716 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1ee/0x430 lib/kobject.c:733
 nfc_free_device include/net/nfc/nfc.h:213 [inline]
 nci_free_device+0x38/0x50 net/nfc/nci/core.c:1209
 virtual_ncidev_close+0x70/0x90 drivers/nfc/virtual_ncidev.c:164
 __fput+0x3cc/0xa10 fs/file_table.c:394
 __do_sys_close fs/open.c:1590 [inline]
 __se_sys_close+0x15f/0x220 fs/open.c:1575
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

The buggy address belongs to the object at ffff888020c66000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1352 bytes inside of
 freed 2048-byte region [ffff888020c66000, ffff888020c66800)

The buggy address belongs to the physical page:
page:ffffea0000831800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x20c60
head:ffffea0000831800 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888012c42000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000080008 00000001ffffffff 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 8, tgid 8 (kworker/0:0), ts 87575041484, free_ts 86099705668
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1537
 prep_new_page mm/page_alloc.c:1544 [inline]
 get_page_from_freelist+0x339a/0x3530 mm/page_alloc.c:3312
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4568
 alloc_pages_mpol+0x3de/0x640 mm/mempolicy.c:2133
 alloc_slab_page+0x6a/0x160 mm/slub.c:1870
 allocate_slab mm/slub.c:2017 [inline]
 new_slab+0x84/0x2f0 mm/slub.c:2070
 ___slab_alloc+0xc85/0x1310 mm/slub.c:3223
 __slab_alloc mm/slub.c:3322 [inline]
 __slab_alloc_node mm/slub.c:3375 [inline]
 slab_alloc_node mm/slub.c:3468 [inline]
 __kmem_cache_alloc_node+0x21d/0x300 mm/slub.c:3517
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node_track_caller+0xa5/0x230 mm/slab_common.c:1027
 kmalloc_reserve+0xf3/0x260 net/core/skbuff.c:582
 __alloc_skb+0x1b1/0x420 net/core/skbuff.c:651
 alloc_skb include/linux/skbuff.h:1286 [inline]
 alloc_skb_with_frags+0xc3/0x780 net/core/skbuff.c:6331
 sock_alloc_send_pskb+0x919/0xa50 net/core/sock.c:2780
 sock_alloc_send_skb include/net/sock.h:1884 [inline]
 mld_newpack+0x1c9/0xa90 net/ipv6/mcast.c:1746
 add_grhead net/ipv6/mcast.c:1849 [inline]
 add_grec+0x148d/0x1990 net/ipv6/mcast.c:1987
 mld_send_cr net/ipv6/mcast.c:2113 [inline]
 mld_ifc_work+0x6bf/0xb20 net/ipv6/mcast.c:2650
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1137 [inline]
 free_unref_page_prepare+0x92a/0xa50 mm/page_alloc.c:2347
 free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487
 discard_slab mm/slub.c:2116 [inline]
 __unfreeze_partials+0x1dc/0x220 mm/slub.c:2655
 put_cpu_partial+0x17b/0x250 mm/slub.c:2731
 __slab_free+0x2b6/0x390 mm/slub.c:3679
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x14b/0x160 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x23/0x70 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6c/0x3c0 mm/slab.h:763
 slab_alloc_node mm/slub.c:3478 [inline]
 slab_alloc mm/slub.c:3486 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3493 [inline]
 kmem_cache_alloc_lru+0x100/0x2c0 mm/slub.c:3509
 __d_alloc+0x31/0x710 fs/dcache.c:1768
 d_alloc fs/dcache.c:1848 [inline]
 d_alloc_parallel+0xe1/0x1590 fs/dcache.c:2637
 __lookup_slow+0x117/0x3e0 fs/namei.c:1679
 lookup_slow+0x53/0x70 fs/namei.c:1711
 walk_component fs/namei.c:2002 [inline]
 link_path_walk+0x9c8/0xe70 fs/namei.c:2329
 path_openat+0x25d/0x3280 fs/namei.c:3775

Memory state around the buggy address:
 ffff888020c66400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888020c66480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888020c66500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff888020c66580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888020c66600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Tested on:

commit:         b85ea95d Linux 6.7-rc1
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=113c6a57680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b5bf1661f609e7f0
dashboard link: https://syzkaller.appspot.com/bug?extid=bbe84a4010eeea00982d
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12d9c9a8e80000