Message-ID: <66fbf66e.050a0220.f28ec.04a2.GAE@google.com>
Date: Tue, 01 Oct 2024 06:17:34 -0700
From: syzbot <syzbot+9265e754091c2d27ea29@...kaller.appspotmail.com>
To: surajsonawane0215@...il.com
Cc: surajsonawane0215@...il.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in
 l2cap_sock_ready_cb (2)

> This fix ensures that the parent socket is valid and not marked as dead
> before invoking sk_data_ready, preventing potential slab-use-after-free
> issues. It adds a check for SOCK_DEAD to avoid accessing freed or invalid
> memory.
>
> #syz test

This crash does not have a reproducer. I cannot test it.

>
> Signed-off-by: SurajSonawane2415 <surajsonawane0215@...il.com>
> ---
>  net/bluetooth/l2cap_sock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
> index ba437c6f6..fa9d6dd7e 100644
> --- a/net/bluetooth/l2cap_sock.c
> +++ b/net/bluetooth/l2cap_sock.c
> @@ -1666,7 +1666,7 @@ static void l2cap_sock_ready_cb(struct l2cap_chan
> *chan)
>   sk->sk_state = BT_CONNECTED;
>   sk->sk_state_change(sk);
>
> - if (parent)
> + if (parent && sock_flag(parent, SOCK_DEAD) == 0)
>   parent->sk_data_ready(parent);
>
>   release_sock(sk);
> -- 
> 2.34.1
>
> On Tue, Oct 1, 2024 at 3:45 PM syzbot <
> syzbot+9265e754091c2d27ea29@...kaller.appspotmail.com> wrote:
>
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit:    5f5673607153 Merge branch 'for-next/core' into for-kernelci
>> git tree:       git://
>> git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
>> console output: https://syzkaller.appspot.com/x/log.txt?x=12881980580000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=dedbcb1ff4387972
>> dashboard link:
>> https://syzkaller.appspot.com/bug?extid=9265e754091c2d27ea29
>> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for
>> Debian) 2.40
>> userspace arch: arm64
>>
>> Unfortunately, I don't have any reproducer for this issue yet.
>>
>> Downloadable assets:
>> disk image:
>> https://storage.googleapis.com/syzbot-assets/40172aed5414/disk-5f567360.raw.xz
>> vmlinux:
>> https://storage.googleapis.com/syzbot-assets/58372f305e9d/vmlinux-5f567360.xz
>> kernel image:
>> https://storage.googleapis.com/syzbot-assets/d2aae6fa798f/Image-5f567360.gz.xz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the
>> commit:
>> Reported-by: syzbot+9265e754091c2d27ea29@...kaller.appspotmail.com
>>
>> kobject: kobject_add_internal failed for hci0:201 with -EEXIST, don't try
>> to register things with the same name in the same directory.
>> Bluetooth: hci0: failed to register connection device
>> ==================================================================
>> BUG: KASAN: slab-use-after-free in l2cap_sock_ready_cb+0xc4/0x130
>> net/bluetooth/l2cap_sock.c:1670
>> Read of size 8 at addr ffff0000da74b188 by task kworker/u9:6/6425
>>
>> CPU: 0 UID: 0 PID: 6425 Comm: kworker/u9:6 Not tainted
>> 6.11.0-rc7-syzkaller-g5f5673607153 #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 08/06/2024
>> Workqueue: hci0 hci_rx_work
>> Call trace:
>>  dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:319
>>  show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:326
>>  __dump_stack lib/dump_stack.c:93 [inline]
>>  dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:119
>>  print_address_description mm/kasan/report.c:377 [inline]
>>  print_report+0x198/0x538 mm/kasan/report.c:488
>>  kasan_report+0xd8/0x138 mm/kasan/report.c:601
>>  __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381
>>  l2cap_sock_ready_cb+0xc4/0x130 net/bluetooth/l2cap_sock.c:1670
>>  l2cap_chan_ready net/bluetooth/l2cap_core.c:1256 [inline]
>>  l2cap_le_start+0xa6c/0x1384 net/bluetooth/l2cap_core.c:1368
>>  l2cap_conn_ready net/bluetooth/l2cap_core.c:1624 [inline]
>>  l2cap_connect_cfm+0x57c/0xe24 net/bluetooth/l2cap_core.c:7286
>>  hci_connect_cfm+0xa0/0x13c include/net/bluetooth/hci_core.h:1960
>>  le_conn_complete_evt+0xa1c/0xf0c net/bluetooth/hci_event.c:5761
>>  hci_le_conn_complete_evt+0x114/0x404 net/bluetooth/hci_event.c:5787
>>  hci_le_meta_evt+0x2a4/0x478 net/bluetooth/hci_event.c:7135
>>  hci_event_func net/bluetooth/hci_event.c:7443 [inline]
>>  hci_event_packet+0x890/0x106c net/bluetooth/hci_event.c:7498
>>  hci_rx_work+0x318/0xa80 net/bluetooth/hci_core.c:4023
>>  process_one_work+0x79c/0x15b8 kernel/workqueue.c:3231
>>  process_scheduled_works kernel/workqueue.c:3312 [inline]
>>  worker_thread+0x978/0xec4 kernel/workqueue.c:3389
>>  kthread+0x288/0x310 kernel/kthread.c:389
>>  ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
>>
>> Allocated by task 6795:
>>  kasan_save_stack mm/kasan/common.c:47 [inline]
>>  kasan_save_track+0x40/0x78 mm/kasan/common.c:68
>>  kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:565
>>  poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
>>  __kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:387
>>  kasan_kmalloc include/linux/kasan.h:211 [inline]
>>  __do_kmalloc_node mm/slub.c:4162 [inline]
>>  __kmalloc_noprof+0x2a4/0x498 mm/slub.c:4174
>>  kmalloc_noprof include/linux/slab.h:685 [inline]
>>  sk_prot_alloc+0xc4/0x1f0 net/core/sock.c:2096
>>  sk_alloc+0x44/0x3f0 net/core/sock.c:2149
>>  bt_sock_alloc+0x4c/0x304 net/bluetooth/af_bluetooth.c:148
>>  l2cap_sock_alloc net/bluetooth/l2cap_sock.c:1877 [inline]
>>  l2cap_sock_create+0x140/0x2b8 net/bluetooth/l2cap_sock.c:1917
>>  bt_sock_create+0x14c/0x248 net/bluetooth/af_bluetooth.c:132
>>  __sock_create+0x43c/0x884 net/socket.c:1571
>>  sock_create net/socket.c:1622 [inline]
>>  __sys_socket_create net/socket.c:1659 [inline]
>>  __sys_socket+0x134/0x340 net/socket.c:1706
>>  __do_sys_socket net/socket.c:1720 [inline]
>>  __se_sys_socket net/socket.c:1718 [inline]
>>  __arm64_sys_socket+0x7c/0x94 net/socket.c:1718
>>  __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
>>  invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
>>  el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
>>  do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
>>  el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712
>>  el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
>>  el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
>>
>> Freed by task 6794:
>>  kasan_save_stack mm/kasan/common.c:47 [inline]
>>  kasan_save_track+0x40/0x78 mm/kasan/common.c:68
>>  kasan_save_free_info+0x54/0x6c mm/kasan/generic.c:579
>>  poison_slab_object+0x128/0x180 mm/kasan/common.c:240
>>  __kasan_slab_free+0x3c/0x70 mm/kasan/common.c:256
>>  kasan_slab_free include/linux/kasan.h:184 [inline]
>>  slab_free_hook mm/slub.c:2256 [inline]
>>  slab_free mm/slub.c:4477 [inline]
>>  kfree+0x154/0x3e0 mm/slub.c:4598
>>  sk_prot_free net/core/sock.c:2132 [inline]
>>  __sk_destruct+0x4b8/0x74c net/core/sock.c:2224
>>  sk_destruct net/core/sock.c:2239 [inline]
>>  __sk_free+0x388/0x4f4 net/core/sock.c:2250
>>  sk_free+0x60/0xc8 net/core/sock.c:2261
>>  sock_put include/net/sock.h:1884 [inline]
>>  l2cap_sock_kill+0x12c/0x234 net/bluetooth/l2cap_sock.c:1250
>>  l2cap_sock_release+0x138/0x1b4 net/bluetooth/l2cap_sock.c:1421
>>  __sock_release net/socket.c:659 [inline]
>>  sock_close+0xa4/0x1e8 net/socket.c:1421
>>  __fput+0x1bc/0x774 fs/file_table.c:422
>>  ____fput+0x20/0x30 fs/file_table.c:450
>>  task_work_run+0x230/0x2e0 kernel/task_work.c:228
>>  resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
>>  do_notify_resume+0x178/0x1f4 arch/arm64/kernel/entry-common.c:151
>>  exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
>>  exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
>>  el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:713
>>  el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
>>  el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
>>
>> The buggy address belongs to the object at ffff0000da74b000
>>  which belongs to the cache kmalloc-2k of size 2048
>> The buggy address is located 392 bytes inside of
>>  freed 2048-byte region [ffff0000da74b000, ffff0000da74b800)
>>
>> The buggy address belongs to the physical page:
>> page: refcount:1 mapcount:0 mapping:0000000000000000
>> index:0xffff0000da74e000 pfn:0x11a748
>> head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
>> flags: 0x5ffc00000000240(workingset|head|node=0|zone=2|lastcpupid=0x7ff)
>> page_type: 0xfdffffff(slab)
>> raw: 05ffc00000000240 ffff0000c0002000 fffffdffc369c610 fffffdffc3093810
>> raw: ffff0000da74e000 0000000000080006 00000001fdffffff 0000000000000000
>> head: 05ffc00000000240 ffff0000c0002000 fffffdffc369c610 fffffdffc3093810
>> head: ffff0000da74e000 0000000000080006 00000001fdffffff 0000000000000000
>> head: 05ffc00000000003 fffffdffc369d201 ffffffffffffffff 0000000000000000
>> head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>>  ffff0000da74b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff0000da74b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> >ffff0000da74b180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>                       ^
>>  ffff0000da74b200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff0000da74b280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ==================================================================
>>
>>
>> ---
>> This report is generated by a bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for more information about syzbot.
>> syzbot engineers can be reached at syzkaller@...glegroups.com.
>>
>> syzbot will keep track of this issue. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>>
>> If the report is already addressed, let syzbot know by replying with:
>> #syz fix: exact-commit-title
>>
>> If you want to overwrite report's subsystems, reply with:
>> #syz set subsystems: new-subsystem
>> (See the list of subsystem names on the web dashboard)
>>
>> If the report is a duplicate of another one, reply with:
>> #syz dup: exact-subject-of-another-report
>>
>> If you want to undo deduplication, reply with:
>> #syz undup
>>
>> --
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>> .
>>

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