[syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_sock_ready_cb (2)

[syzbot]

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+9265e7...@syzkaller.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
==================================================================


---
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[syzbot]

> 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 <surajson...@gmail.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

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