[syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_connect (2)

[syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_connect (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    5f583a3162ff Merge tag 'rust-fixes-6.10' of https://github..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11170741980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f413acf5b1eb4093
dashboard link: https://syzkaller.appspot.com/bug?extid=c12e2f941af1feb5632c
compiler:       gcc (Debian 12.2.0-14) 12.2.0, 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/f530c7950839/disk-5f583a31.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b4f810bbc13e/vmlinux-5f583a31.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a49ec6dadbad/bzImage-5f583a31.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c12e2f941af1feb5632c@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
Read of size 8 at addr ffff88802af53000 by task kworker/u9:4/5114

CPU: 1 PID: 5114 Comm: kworker/u9:4 Not tainted 6.10.0-rc4-syzkaller-00301-g5f583a3162ff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: hci1 hci_rx_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:488
 kasan_report+0xd9/0x110 mm/kasan/report.c:601
 l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
 l2cap_connect_req net/bluetooth/l2cap_core.c:4080 [inline]
 l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:4772 [inline]
 l2cap_sig_channel net/bluetooth/l2cap_core.c:5543 [inline]
 l2cap_recv_frame+0xf07/0x8e50 net/bluetooth/l2cap_core.c:6821
 l2cap_recv_acldata+0x9ac/0xb60 net/bluetooth/l2cap_core.c:7510
 hci_acldata_packet net/bluetooth/hci_core.c:3842 [inline]
 hci_rx_work+0xaa7/0x1610 net/bluetooth/hci_core.c:4079
 process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 4480:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:387
 kmalloc_noprof include/linux/slab.h:660 [inline]
 kzalloc_noprof include/linux/slab.h:778 [inline]
 l2cap_conn_add.part.0+0x60/0xa60 net/bluetooth/l2cap_core.c:6864
 l2cap_conn_add net/bluetooth/l2cap_core.c:69 [inline]
 l2cap_connect_cfm+0x428/0xf80 net/bluetooth/l2cap_core.c:7241
 hci_connect_cfm include/net/bluetooth/hci_core.h:1970 [inline]
 hci_remote_features_evt+0x548/0x9e0 net/bluetooth/hci_event.c:3721
 hci_event_func net/bluetooth/hci_event.c:7417 [inline]
 hci_event_packet+0x9e3/0x1170 net/bluetooth/hci_event.c:7469
 hci_rx_work+0x2c4/0x1610 net/bluetooth/hci_core.c:4074
 process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Freed by task 5112:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
 poison_slab_object+0xf7/0x160 mm/kasan/common.c:240
 __kasan_slab_free+0x32/0x50 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2196 [inline]
 slab_free mm/slub.c:4437 [inline]
 kfree+0x12a/0x3b0 mm/slub.c:4558
 l2cap_conn_free net/bluetooth/l2cap_core.c:1810 [inline]
 kref_put include/linux/kref.h:65 [inline]
 l2cap_conn_put net/bluetooth/l2cap_core.c:1822 [inline]
 l2cap_conn_del+0x59d/0x740 net/bluetooth/l2cap_core.c:1802
 l2cap_connect_cfm+0x9e6/0xf80 net/bluetooth/l2cap_core.c:7237
 hci_connect_cfm include/net/bluetooth/hci_core.h:1970 [inline]
 hci_conn_failed+0x1c3/0x370 net/bluetooth/hci_conn.c:1257
 hci_abort_conn_sync+0x75a/0xb50 net/bluetooth/hci_sync.c:5450
 abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2909
 hci_cmd_sync_work+0x1a4/0x410 net/bluetooth/hci_sync.c:310
 process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Last potentially related work creation:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xba/0xd0 mm/kasan/generic.c:541
 insert_work+0x36/0x230 kernel/workqueue.c:2207
 __queue_work+0x944/0x1020 kernel/workqueue.c:2359
 call_timer_fn+0x1a0/0x610 kernel/time/timer.c:1792
 expire_timers kernel/time/timer.c:1838 [inline]
 __run_timers+0x567/0xaf0 kernel/time/timer.c:2417
 __run_timer_base kernel/time/timer.c:2428 [inline]
 __run_timer_base kernel/time/timer.c:2421 [inline]
 run_timer_base+0x111/0x190 kernel/time/timer.c:2437
 run_timer_softirq+0x1a/0x40 kernel/time/timer.c:2447
 handle_softirqs+0x216/0x8f0 kernel/softirq.c:554
 __do_softirq kernel/softirq.c:588 [inline]
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu kernel/softirq.c:637 [inline]
 irq_exit_rcu+0xbb/0x120 kernel/softirq.c:649
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0x95/0xb0 arch/x86/kernel/apic/apic.c:1043
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

Second to last potentially related work creation:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xba/0xd0 mm/kasan/generic.c:541
 insert_work+0x36/0x230 kernel/workqueue.c:2207
 __queue_work+0x525/0x1020 kernel/workqueue.c:2363
 queue_work_on+0x11a/0x140 kernel/workqueue.c:2410
 queue_work include/linux/workqueue.h:621 [inline]
 l2cap_conn_ready net/bluetooth/l2cap_core.c:1640 [inline]
 l2cap_connect_cfm+0x9c9/0xf80 net/bluetooth/l2cap_core.c:7282
 hci_connect_cfm include/net/bluetooth/hci_core.h:1970 [inline]
 hci_remote_features_evt+0x548/0x9e0 net/bluetooth/hci_event.c:3721
 hci_event_func net/bluetooth/hci_event.c:7417 [inline]
 hci_event_packet+0x9e3/0x1170 net/bluetooth/hci_event.c:7469
 hci_rx_work+0x2c4/0x1610 net/bluetooth/hci_core.c:4074
 process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff88802af53000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 0 bytes inside of
 freed 1024-byte region [ffff88802af53000, ffff88802af53400)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2af50
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffefff(slab)
raw: 00fff00000000040 ffff888015441dc0 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000
head: 00fff00000000040 ffff888015441dc0 0000000000000000 dead000000000001
head: 0000000000000000 0000000000100010 00000001ffffefff 0000000000000000
head: 00fff00000000003 ffffea0000abd401 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4752, tgid 4752 (dhcpcd), ts 66098690934, free_ts 66038999175
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x2d1/0x350 mm/page_alloc.c:1468
 prep_new_page mm/page_alloc.c:1476 [inline]
 get_page_from_freelist+0x136a/0x2e50 mm/page_alloc.c:3420
 __alloc_pages_noprof+0x22b/0x2460 mm/page_alloc.c:4678
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x56/0x110 mm/slub.c:2265
 allocate_slab mm/slub.c:2428 [inline]
 new_slab+0x84/0x260 mm/slub.c:2481
 ___slab_alloc+0xdac/0x1870 mm/slub.c:3667
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3757
 __slab_alloc_node mm/slub.c:3810 [inline]
 slab_alloc_node mm/slub.c:3989 [inline]
 __do_kmalloc_node mm/slub.c:4121 [inline]
 kmalloc_node_track_caller_noprof+0x355/0x430 mm/slub.c:4142
 kmemdup_noprof+0x29/0x60 mm/util.c:131
 kmemdup_noprof include/linux/fortify-string.h:757 [inline]
 bpf_migrate_filter+0xc6/0x390 net/core/filter.c:1268
 bpf_prepare_filter+0x183/0x380 net/core/filter.c:1354
 bpf_prog_create_from_user+0x1e4/0x2d0 net/core/filter.c:1448
 seccomp_prepare_filter kernel/seccomp.c:680 [inline]
 seccomp_prepare_user_filter kernel/seccomp.c:717 [inline]
 seccomp_set_mode_filter kernel/seccomp.c:1935 [inline]
 do_seccomp+0x7b6/0x2580 kernel/seccomp.c:2055
 prctl_set_seccomp+0x4b/0x70 kernel/seccomp.c:2108
 __do_sys_prctl+0xc83/0x1e40 kernel/sys.c:2539
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
page last free pid 4747 tgid 4747 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1088 [inline]
 free_unref_page+0x64a/0xe40 mm/page_alloc.c:2583
 __put_partials+0x14c/0x170 mm/slub.c:2995
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4e/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x192/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:322
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3941 [inline]
 slab_alloc_node mm/slub.c:4001 [inline]
 kmem_cache_alloc_lru_noprof+0x121/0x2f0 mm/slub.c:4020
 shmem_alloc_inode+0x25/0x50 mm/shmem.c:4468
 alloc_inode+0x5d/0x230 fs/inode.c:261
 new_inode_pseudo fs/inode.c:1007 [inline]
 new_inode+0x22/0x270 fs/inode.c:1033
 __shmem_get_inode mm/shmem.c:2503 [inline]
 shmem_get_inode+0x194/0xe80 mm/shmem.c:2574
 shmem_mknod+0x66/0x240 mm/shmem.c:3268
 shmem_mkdir+0x31/0x60 mm/shmem.c:3329
 vfs_mkdir+0x57d/0x860 fs/namei.c:4131
 do_mkdirat+0x301/0x3a0 fs/namei.c:4154
 __do_sys_mkdir fs/namei.c:4174 [inline]
 __se_sys_mkdir fs/namei.c:4172 [inline]
 __x64_sys_mkdir+0xf1/0x140 fs/namei.c:4172
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83

Memory state around the buggy address:
 ffff88802af52f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802af52f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802af53000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88802af53080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802af53100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_connect (2)

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    788220eee30d Merge tag 'pm-6.11-rc7' of git://git.kernel.o..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10502bc7980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=57042fe37c7ee7c2
dashboard link: https://syzkaller.appspot.com/bug?extid=c12e2f941af1feb5632c
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11da6f29980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1304189f980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e618b7c8e5a2/disk-788220ee.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/333bb524a2ba/vmlinux-788220ee.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ad1779f24bb2/bzImage-788220ee.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c12e2f941af1feb5632c@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
Read of size 8 at addr ffff8880241e9800 by task kworker/u9:0/54

CPU: 0 UID: 0 PID: 54 Comm: kworker/u9:0 Not tainted 6.11.0-rc6-syzkaller-00268-g788220eee30d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: hci2 hci_rx_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:488
 kasan_report+0xd9/0x110 mm/kasan/report.c:601
 l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
 l2cap_connect_req net/bluetooth/l2cap_core.c:4080 [inline]
 l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:4772 [inline]
 l2cap_sig_channel net/bluetooth/l2cap_core.c:5543 [inline]
 l2cap_recv_frame+0xf0b/0x8eb0 net/bluetooth/l2cap_core.c:6825
 l2cap_recv_acldata+0x9b4/0xb70 net/bluetooth/l2cap_core.c:7514
 hci_acldata_packet net/bluetooth/hci_core.c:3791 [inline]
 hci_rx_work+0xaab/0x1610 net/bluetooth/hci_core.c:4028
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 5253:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:387
 kmalloc_noprof include/linux/slab.h:681 [inline]
 kzalloc_noprof include/linux/slab.h:807 [inline]
 l2cap_conn_add.part.0+0x60/0xa60 net/bluetooth/l2cap_core.c:6868
 l2cap_conn_add net/bluetooth/l2cap_core.c:69 [inline]
 l2cap_connect_cfm+0x428/0xf80 net/bluetooth/l2cap_core.c:7245
 hci_connect_cfm include/net/bluetooth/hci_core.h:1960 [inline]
 hci_remote_features_evt+0x548/0x9e0 net/bluetooth/hci_event.c:3721
 hci_event_func net/bluetooth/hci_event.c:7446 [inline]
 hci_event_packet+0x9eb/0x1180 net/bluetooth/hci_event.c:7498
 hci_rx_work+0x2c6/0x1610 net/bluetooth/hci_core.c:4023
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Freed by task 5245:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
 poison_slab_object+0xf7/0x160 mm/kasan/common.c:240
 __kasan_slab_free+0x32/0x50 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+0x12a/0x3b0 mm/slub.c:4598
 l2cap_conn_free net/bluetooth/l2cap_core.c:1810 [inline]
 kref_put include/linux/kref.h:65 [inline]
 l2cap_conn_put net/bluetooth/l2cap_core.c:1822 [inline]
 l2cap_conn_del+0x59d/0x730 net/bluetooth/l2cap_core.c:1802
 l2cap_connect_cfm+0x9e6/0xf80 net/bluetooth/l2cap_core.c:7241
 hci_connect_cfm include/net/bluetooth/hci_core.h:1960 [inline]
 hci_conn_failed+0x1c3/0x370 net/bluetooth/hci_conn.c:1265
 hci_abort_conn_sync+0x75a/0xb50 net/bluetooth/hci_sync.c:5583
 abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2917
 hci_cmd_sync_work+0x1a4/0x410 net/bluetooth/hci_sync.c:328
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Last potentially related work creation:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xba/0xd0 mm/kasan/generic.c:541
 insert_work+0x36/0x230 kernel/workqueue.c:2185
 __queue_work+0x97e/0x1070 kernel/workqueue.c:2341
 call_timer_fn+0x1a0/0x610 kernel/time/timer.c:1792
 expire_timers kernel/time/timer.c:1838 [inline]
 __run_timers+0x567/0xaf0 kernel/time/timer.c:2417
 __run_timer_base kernel/time/timer.c:2428 [inline]
 __run_timer_base kernel/time/timer.c:2421 [inline]
 run_timer_base+0x111/0x190 kernel/time/timer.c:2437
 run_timer_softirq+0x1a/0x40 kernel/time/timer.c:2447
 handle_softirqs+0x216/0x8f0 kernel/softirq.c:554
 __do_softirq kernel/softirq.c:588 [inline]
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu kernel/softirq.c:637 [inline]
 irq_exit_rcu+0xbb/0x120 kernel/softirq.c:649
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0x95/0xb0 arch/x86/kernel/apic/apic.c:1043
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

Second to last potentially related work creation:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xba/0xd0 mm/kasan/generic.c:541
 insert_work+0x36/0x230 kernel/workqueue.c:2185
 __queue_work+0x3f8/0x1070 kernel/workqueue.c:2345
 queue_work_on+0x11a/0x140 kernel/workqueue.c:2392
 queue_work include/linux/workqueue.h:621 [inline]
 l2cap_conn_ready net/bluetooth/l2cap_core.c:1640 [inline]
 l2cap_connect_cfm+0x9c9/0xf80 net/bluetooth/l2cap_core.c:7286
 hci_connect_cfm include/net/bluetooth/hci_core.h:1960 [inline]
 hci_remote_features_evt+0x548/0x9e0 net/bluetooth/hci_event.c:3721
 hci_event_func net/bluetooth/hci_event.c:7446 [inline]
 hci_event_packet+0x9eb/0x1180 net/bluetooth/hci_event.c:7498
 hci_rx_work+0x2c6/0x1610 net/bluetooth/hci_core.c:4023
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff8880241e9800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 0 bytes inside of
 freed 1024-byte region [ffff8880241e9800, ffff8880241e9c00)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x241e8
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 ffff88801ac41dc0 ffffea00007cac00 dead000000000002
raw: 0000000000000000 0000000000100010 00000001fdffffff 0000000000000000
head: 00fff00000000040 ffff88801ac41dc0 ffffea00007cac00 dead000000000002
head: 0000000000000000 0000000000100010 00000001fdffffff 0000000000000000
head: 00fff00000000003 ffffea0000907a01 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 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4642, tgid 4642 (init), ts 27796307015, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x2d1/0x350 mm/page_alloc.c:1500
 prep_new_page mm/page_alloc.c:1508 [inline]
 get_page_from_freelist+0x1351/0x2e50 mm/page_alloc.c:3446
 __alloc_pages_noprof+0x22b/0x2460 mm/page_alloc.c:4702
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 alloc_slab_page+0x4e/0xf0 mm/slub.c:2325
 allocate_slab mm/slub.c:2488 [inline]
 new_slab+0x84/0x260 mm/slub.c:2541
 ___slab_alloc+0xdac/0x1870 mm/slub.c:3727
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3817
 __slab_alloc_node mm/slub.c:3870 [inline]
 slab_alloc_node mm/slub.c:4029 [inline]
 __do_kmalloc_node mm/slub.c:4161 [inline]
 __kmalloc_noprof+0x367/0x400 mm/slub.c:4174
 kmalloc_noprof include/linux/slab.h:685 [inline]
 kzalloc_noprof include/linux/slab.h:807 [inline]
 tomoyo_init_log+0x13ca/0x2180 security/tomoyo/audit.c:275
 tomoyo_supervisor+0x30c/0xea0 security/tomoyo/common.c:2089
 tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
 tomoyo_env_perm+0x193/0x210 security/tomoyo/environ.c:63
 tomoyo_environ security/tomoyo/domain.c:672 [inline]
 tomoyo_find_next_domain+0xef9/0x2020 security/tomoyo/domain.c:878
 tomoyo_bprm_check_security security/tomoyo/tomoyo.c:102 [inline]
 tomoyo_bprm_check_security+0x12e/0x1d0 security/tomoyo/tomoyo.c:92
 security_bprm_check+0x65/0xb0 security/security.c:1191
 search_binary_handler fs/exec.c:1815 [inline]
 exec_binprm fs/exec.c:1869 [inline]
 bprm_execve fs/exec.c:1920 [inline]
 bprm_execve+0x642/0x1960 fs/exec.c:1896
 do_execveat_common.isra.0+0x4f1/0x630 fs/exec.c:2027
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8880241e9700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880241e9780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880241e9800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8880241e9880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880241e9900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Edward Adam Davis]

[Syzbot reported]
BUG: KASAN: slab-use-after-free in l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
Read of size 8 at addr ffff8880241e9800 by task kworker/u9:0/54

CPU: 0 UID: 0 PID: 54 Comm: kworker/u9:0 Not tainted 6.11.0-rc6-syzkaller-00268-g788220eee30d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: hci2 hci_rx_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:488
 kasan_report+0xd9/0x110 mm/kasan/report.c:601
 l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
 l2cap_connect_req net/bluetooth/l2cap_core.c:4080 [inline]
 l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:4772 [inline]
 l2cap_sig_channel net/bluetooth/l2cap_core.c:5543 [inline]
 l2cap_recv_frame+0xf0b/0x8eb0 net/bluetooth/l2cap_core.c:6825
 l2cap_recv_acldata+0x9b4/0xb70 net/bluetooth/l2cap_core.c:7514
 hci_acldata_packet net/bluetooth/hci_core.c:3791 [inline]
 hci_rx_work+0xaab/0x1610 net/bluetooth/hci_core.c:4028
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
...

Freed by task 5245:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
 poison_slab_object+0xf7/0x160 mm/kasan/common.c:240
 __kasan_slab_free+0x32/0x50 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+0x12a/0x3b0 mm/slub.c:4598
 l2cap_conn_free net/bluetooth/l2cap_core.c:1810 [inline]
 kref_put include/linux/kref.h:65 [inline]
 l2cap_conn_put net/bluetooth/l2cap_core.c:1822 [inline]
 l2cap_conn_del+0x59d/0x730 net/bluetooth/l2cap_core.c:1802
 l2cap_connect_cfm+0x9e6/0xf80 net/bluetooth/l2cap_core.c:7241
 hci_connect_cfm include/net/bluetooth/hci_core.h:1960 [inline]
 hci_conn_failed+0x1c3/0x370 net/bluetooth/hci_conn.c:1265
 hci_abort_conn_sync+0x75a/0xb50 net/bluetooth/hci_sync.c:5583
 abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2917
 hci_cmd_sync_work+0x1a4/0x410 net/bluetooth/hci_sync.c:328
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

[Analysis] 
There was a data race when accessing conn in hci_rx_work and hci_cmd_sync_work.
This is because the hci dev lock was prematurely exited when executing
hci_acldata_macket() in hci_rx_work, which resulted in it being released
by hci_cmd_sync_work when accessing conn outside the lock.

Reported-and-tested-by: syzbot+c12e2f941af1feb5632c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=c12e2f941af1feb5632c
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 net/bluetooth/hci_core.c   | 3 ++-
 net/bluetooth/l2cap_core.c | 2 --
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index f25a21f532aa..4f7b45bb863f 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3776,18 +3776,19 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 
 	hci_dev_lock(hdev);
 	conn = hci_conn_hash_lookup_handle(hdev, handle);
-	hci_dev_unlock(hdev);
 
 	if (conn) {
 		hci_conn_enter_active_mode(conn, BT_POWER_FORCE_ACTIVE_OFF);
 
 		/* Send to upper protocol */
 		l2cap_recv_acldata(conn, skb, flags);
+		hci_dev_unlock(hdev);
 		return;
 	} else {
 		bt_dev_err(hdev, "ACL packet for unknown connection handle %d",
 			   handle);
 	}
+	hci_dev_unlock(hdev);
 
 	kfree_skb(skb);
 }
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 9988ba382b68..b948b0a3b2f2 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4072,10 +4072,8 @@ static int l2cap_connect_req(struct l2cap_conn *conn,
 	if (cmd_len < sizeof(struct l2cap_conn_req))
 		return -EPROTO;
 
-	hci_dev_lock(hdev);
 	if (hci_dev_test_flag(hdev, HCI_MGMT))
 		mgmt_device_connected(hdev, hcon, NULL, 0);
-	hci_dev_unlock(hdev);
 
 	l2cap_connect(conn, cmd, data, L2CAP_CONN_RSP);
 	return 0;
-- 
2.43.0

Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_connect (2)

[syzbot]

syzbot has bisected this issue to:

commit 5af1f84ed13a416297ab9ced7537f4d5ae7f329a
Author: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Date:   Thu Aug 3 18:04:51 2023 +0000

    Bluetooth: hci_sync: Fix UAF on hci_abort_conn_sync

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12477bc7980000
start commit:   788220eee30d Merge tag 'pm-6.11-rc7' of git://git.kernel.o..
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=11477bc7980000
console output: https://syzkaller.appspot.com/x/log.txt?x=16477bc7980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=57042fe37c7ee7c2
dashboard link: https://syzkaller.appspot.com/bug?extid=c12e2f941af1feb5632c
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11da6f29980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1304189f980000

Reported-by: syzbot+c12e2f941af1feb5632c@syzkaller.appspotmail.com
Fixes: 5af1f84ed13a ("Bluetooth: hci_sync: Fix UAF on hci_abort_conn_sync")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Re: [PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Luiz Augusto von Dentz]

Hi Edward,

On Sun, Sep 8, 2024 at 3:22 AM Edward Adam Davis <eadavis@qq.com> wrote:
>
> [Syzbot reported]
> BUG: KASAN: slab-use-after-free in l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
> Read of size 8 at addr ffff8880241e9800 by task kworker/u9:0/54
>
> CPU: 0 UID: 0 PID: 54 Comm: kworker/u9:0 Not tainted 6.11.0-rc6-syzkaller-00268-g788220eee30d #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
> Workqueue: hci2 hci_rx_work
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:93 [inline]
>  dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
>  print_address_description mm/kasan/report.c:377 [inline]
>  print_report+0xc3/0x620 mm/kasan/report.c:488
>  kasan_report+0xd9/0x110 mm/kasan/report.c:601
>  l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
>  l2cap_connect_req net/bluetooth/l2cap_core.c:4080 [inline]
>  l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:4772 [inline]
>  l2cap_sig_channel net/bluetooth/l2cap_core.c:5543 [inline]
>  l2cap_recv_frame+0xf0b/0x8eb0 net/bluetooth/l2cap_core.c:6825
>  l2cap_recv_acldata+0x9b4/0xb70 net/bluetooth/l2cap_core.c:7514
>  hci_acldata_packet net/bluetooth/hci_core.c:3791 [inline]
>  hci_rx_work+0xaab/0x1610 net/bluetooth/hci_core.c:4028
>  process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
>  process_scheduled_works kernel/workqueue.c:3312 [inline]
>  worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
>  kthread+0x2c1/0x3a0 kernel/kthread.c:389
>  ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> ...
>
> Freed by task 5245:
>  kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
>  kasan_save_track+0x14/0x30 mm/kasan/common.c:68
>  kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
>  poison_slab_object+0xf7/0x160 mm/kasan/common.c:240
>  __kasan_slab_free+0x32/0x50 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+0x12a/0x3b0 mm/slub.c:4598
>  l2cap_conn_free net/bluetooth/l2cap_core.c:1810 [inline]
>  kref_put include/linux/kref.h:65 [inline]
>  l2cap_conn_put net/bluetooth/l2cap_core.c:1822 [inline]
>  l2cap_conn_del+0x59d/0x730 net/bluetooth/l2cap_core.c:1802
>  l2cap_connect_cfm+0x9e6/0xf80 net/bluetooth/l2cap_core.c:7241
>  hci_connect_cfm include/net/bluetooth/hci_core.h:1960 [inline]
>  hci_conn_failed+0x1c3/0x370 net/bluetooth/hci_conn.c:1265
>  hci_abort_conn_sync+0x75a/0xb50 net/bluetooth/hci_sync.c:5583
>  abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2917
>  hci_cmd_sync_work+0x1a4/0x410 net/bluetooth/hci_sync.c:328
>  process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
>  process_scheduled_works kernel/workqueue.c:3312 [inline]
>  worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
>  kthread+0x2c1/0x3a0 kernel/kthread.c:389
>  ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>
> [Analysis]
> There was a data race when accessing conn in hci_rx_work and hci_cmd_sync_work.
> This is because the hci dev lock was prematurely exited when executing
> hci_acldata_macket() in hci_rx_work, which resulted in it being released
> by hci_cmd_sync_work when accessing conn outside the lock.
>
> Reported-and-tested-by: syzbot+c12e2f941af1feb5632c@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=c12e2f941af1feb5632c
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
>  net/bluetooth/hci_core.c   | 3 ++-
>  net/bluetooth/l2cap_core.c | 2 --
>  2 files changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index f25a21f532aa..4f7b45bb863f 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -3776,18 +3776,19 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
>
>         hci_dev_lock(hdev);
>         conn = hci_conn_hash_lookup_handle(hdev, handle);
> -       hci_dev_unlock(hdev);
>
>         if (conn) {
>                 hci_conn_enter_active_mode(conn, BT_POWER_FORCE_ACTIVE_OFF);
>
>                 /* Send to upper protocol */
>                 l2cap_recv_acldata(conn, skb, flags);
> +               hci_dev_unlock(hdev);
>                 return;
>         } else {
>                 bt_dev_err(hdev, "ACL packet for unknown connection handle %d",
>                            handle);
>         }
> +       hci_dev_unlock(hdev);

This is sort of risky, we shouldn't be calling this deep into the
stack with hci_dev_lock held.

>
>         kfree_skb(skb);
>  }
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 9988ba382b68..b948b0a3b2f2 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -4072,10 +4072,8 @@ static int l2cap_connect_req(struct l2cap_conn *conn,
>         if (cmd_len < sizeof(struct l2cap_conn_req))
>                 return -EPROTO;
>
> -       hci_dev_lock(hdev);
>         if (hci_dev_test_flag(hdev, HCI_MGMT))
>                 mgmt_device_connected(hdev, hcon, NULL, 0);
> -       hci_dev_unlock(hdev);

So this might explain why things gets freed while processing the
request, we are locking to call mgmt_device_connected which I suspect
is no longer needed ever since:

commit db11223571d489d1aab575a4ac4b7352d2d54e2f
Author: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Date:   Tue Oct 25 14:12:58 2022 -0700

    Bluetooth: btusb: Default CONFIG_BT_HCIBTUSB_POLL_SYNC=y

    poll_sync has been proven to fix races of USB data and event endpoints
    so this enables it by default.

    Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
    Tested-by: Tedd Ho-Jeong An <tedd.an@intel.com>

Anyway syzbot don't use btusb so I think this might be due some
command pending that the emulator is not responding and instead
sending data, and then there is the issue that 7b064edae38d
("Bluetooth: Fix authentication if acl data comes before remote
feature evt") attempted to fix which I think it actually made it worse
by moving the call to mgmt_device_connected into l2cap_core.c it sort
move the problem but didn't fix the actual problem.

Maybe something like the following would be a better approach:

https://gist.github.com/Vudentz/121a15fa4391b2b1f6c7e8d420a6846e

>
>         l2cap_connect(conn, cmd, data, L2CAP_CONN_RSP);
>         return 0;
> --
> 2.43.0
>


-- 
Luiz Augusto von Dentz

Re: [PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Luiz Augusto von Dentz]

Hi Edward,

On Tue, Sep 10, 2024 at 4:56 PM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Edward,
>
> On Sun, Sep 8, 2024 at 3:22 AM Edward Adam Davis <eadavis@qq.com> wrote:
> >
> > [Syzbot reported]
> > BUG: KASAN: slab-use-after-free in l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
> > Read of size 8 at addr ffff8880241e9800 by task kworker/u9:0/54
> >
> > CPU: 0 UID: 0 PID: 54 Comm: kworker/u9:0 Not tainted 6.11.0-rc6-syzkaller-00268-g788220eee30d #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
> > Workqueue: hci2 hci_rx_work
> > Call Trace:
> >  <TASK>
> >  __dump_stack lib/dump_stack.c:93 [inline]
> >  dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
> >  print_address_description mm/kasan/report.c:377 [inline]
> >  print_report+0xc3/0x620 mm/kasan/report.c:488
> >  kasan_report+0xd9/0x110 mm/kasan/report.c:601
> >  l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
> >  l2cap_connect_req net/bluetooth/l2cap_core.c:4080 [inline]
> >  l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:4772 [inline]
> >  l2cap_sig_channel net/bluetooth/l2cap_core.c:5543 [inline]
> >  l2cap_recv_frame+0xf0b/0x8eb0 net/bluetooth/l2cap_core.c:6825
> >  l2cap_recv_acldata+0x9b4/0xb70 net/bluetooth/l2cap_core.c:7514
> >  hci_acldata_packet net/bluetooth/hci_core.c:3791 [inline]
> >  hci_rx_work+0xaab/0x1610 net/bluetooth/hci_core.c:4028
> >  process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
> >  process_scheduled_works kernel/workqueue.c:3312 [inline]
> >  worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
> >  kthread+0x2c1/0x3a0 kernel/kthread.c:389
> >  ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
> >  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> > ...
> >
> > Freed by task 5245:
> >  kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
> >  kasan_save_track+0x14/0x30 mm/kasan/common.c:68
> >  kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
> >  poison_slab_object+0xf7/0x160 mm/kasan/common.c:240
> >  __kasan_slab_free+0x32/0x50 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+0x12a/0x3b0 mm/slub.c:4598
> >  l2cap_conn_free net/bluetooth/l2cap_core.c:1810 [inline]
> >  kref_put include/linux/kref.h:65 [inline]
> >  l2cap_conn_put net/bluetooth/l2cap_core.c:1822 [inline]
> >  l2cap_conn_del+0x59d/0x730 net/bluetooth/l2cap_core.c:1802
> >  l2cap_connect_cfm+0x9e6/0xf80 net/bluetooth/l2cap_core.c:7241
> >  hci_connect_cfm include/net/bluetooth/hci_core.h:1960 [inline]
> >  hci_conn_failed+0x1c3/0x370 net/bluetooth/hci_conn.c:1265
> >  hci_abort_conn_sync+0x75a/0xb50 net/bluetooth/hci_sync.c:5583
> >  abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2917
> >  hci_cmd_sync_work+0x1a4/0x410 net/bluetooth/hci_sync.c:328
> >  process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
> >  process_scheduled_works kernel/workqueue.c:3312 [inline]
> >  worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
> >  kthread+0x2c1/0x3a0 kernel/kthread.c:389
> >  ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
> >  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> >
> > [Analysis]
> > There was a data race when accessing conn in hci_rx_work and hci_cmd_sync_work.
> > This is because the hci dev lock was prematurely exited when executing
> > hci_acldata_macket() in hci_rx_work, which resulted in it being released
> > by hci_cmd_sync_work when accessing conn outside the lock.
> >
> > Reported-and-tested-by: syzbot+c12e2f941af1feb5632c@syzkaller.appspotmail.com
> > Closes: https://syzkaller.appspot.com/bug?extid=c12e2f941af1feb5632c
> > Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> > ---
> >  net/bluetooth/hci_core.c   | 3 ++-
> >  net/bluetooth/l2cap_core.c | 2 --
> >  2 files changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> > index f25a21f532aa..4f7b45bb863f 100644
> > --- a/net/bluetooth/hci_core.c
> > +++ b/net/bluetooth/hci_core.c
> > @@ -3776,18 +3776,19 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
> >
> >         hci_dev_lock(hdev);
> >         conn = hci_conn_hash_lookup_handle(hdev, handle);
> > -       hci_dev_unlock(hdev);
> >
> >         if (conn) {
> >                 hci_conn_enter_active_mode(conn, BT_POWER_FORCE_ACTIVE_OFF);
> >
> >                 /* Send to upper protocol */
> >                 l2cap_recv_acldata(conn, skb, flags);
> > +               hci_dev_unlock(hdev);
> >                 return;
> >         } else {
> >                 bt_dev_err(hdev, "ACL packet for unknown connection handle %d",
> >                            handle);
> >         }
> > +       hci_dev_unlock(hdev);
>
> This is sort of risky, we shouldn't be calling this deep into the
> stack with hci_dev_lock held.
>
> >
> >         kfree_skb(skb);
> >  }
> > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> > index 9988ba382b68..b948b0a3b2f2 100644
> > --- a/net/bluetooth/l2cap_core.c
> > +++ b/net/bluetooth/l2cap_core.c
> > @@ -4072,10 +4072,8 @@ static int l2cap_connect_req(struct l2cap_conn *conn,
> >         if (cmd_len < sizeof(struct l2cap_conn_req))
> >                 return -EPROTO;
> >
> > -       hci_dev_lock(hdev);
> >         if (hci_dev_test_flag(hdev, HCI_MGMT))
> >                 mgmt_device_connected(hdev, hcon, NULL, 0);
> > -       hci_dev_unlock(hdev);
>
> So this might explain why things gets freed while processing the
> request, we are locking to call mgmt_device_connected which I suspect
> is no longer needed ever since:
>
> commit db11223571d489d1aab575a4ac4b7352d2d54e2f
> Author: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> Date:   Tue Oct 25 14:12:58 2022 -0700
>
>     Bluetooth: btusb: Default CONFIG_BT_HCIBTUSB_POLL_SYNC=y
>
>     poll_sync has been proven to fix races of USB data and event endpoints
>     so this enables it by default.
>
>     Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
>     Tested-by: Tedd Ho-Jeong An <tedd.an@intel.com>
>
> Anyway syzbot don't use btusb so I think this might be due some
> command pending that the emulator is not responding and instead
> sending data, and then there is the issue that 7b064edae38d
> ("Bluetooth: Fix authentication if acl data comes before remote
> feature evt") attempted to fix which I think it actually made it worse
> by moving the call to mgmt_device_connected into l2cap_core.c it sort
> move the problem but didn't fix the actual problem.
>
> Maybe something like the following would be a better approach:
>
> https://gist.github.com/Vudentz/121a15fa4391b2b1f6c7e8d420a6846e

Any comments? Are you still planning to work on this?

> >
> >         l2cap_connect(conn, cmd, data, L2CAP_CONN_RSP);
> >         return 0;
> > --
> > 2.43.0
> >
>
>
> --
> Luiz Augusto von Dentz



-- 
Luiz Augusto von Dentz

Re: [PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Edward Adam Davis]

On Fri, 20 Sep 2024 11:07:05 -0400, Luiz Augusto von Dentz wrote:
> On Tue, Sep 10, 2024 at 4:56 PM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> >
> > Hi Edward,
> >
> > On Sun, Sep 8, 2024 at 3:22 AM Edward Adam Davis <eadavis@qq.com> wrote:
> > >
> > > [Syzbot reported]
> > > BUG: KASAN: slab-use-after-free in l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
> > > Read of size 8 at addr ffff8880241e9800 by task kworker/u9:0/54
> > >
> > > CPU: 0 UID: 0 PID: 54 Comm: kworker/u9:0 Not tainted 6.11.0-rc6-syzkaller-00268-g788220eee30d #0
> > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
> > > Workqueue: hci2 hci_rx_work
> > > Call Trace:
> > >  <TASK>
> > >  __dump_stack lib/dump_stack.c:93 [inline]
> > >  dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
> > >  print_address_description mm/kasan/report.c:377 [inline]
> > >  print_report+0xc3/0x620 mm/kasan/report.c:488
> > >  kasan_report+0xd9/0x110 mm/kasan/report.c:601
> > >  l2cap_connect.constprop.0+0x10d8/0x1270 net/bluetooth/l2cap_core.c:3949
> > >  l2cap_connect_req net/bluetooth/l2cap_core.c:4080 [inline]
> > >  l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:4772 [inline]
> > >  l2cap_sig_channel net/bluetooth/l2cap_core.c:5543 [inline]
> > >  l2cap_recv_frame+0xf0b/0x8eb0 net/bluetooth/l2cap_core.c:6825
> > >  l2cap_recv_acldata+0x9b4/0xb70 net/bluetooth/l2cap_core.c:7514
> > >  hci_acldata_packet net/bluetooth/hci_core.c:3791 [inline]
> > >  hci_rx_work+0xaab/0x1610 net/bluetooth/hci_core.c:4028
> > >  process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
> > >  process_scheduled_works kernel/workqueue.c:3312 [inline]
> > >  worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
> > >  kthread+0x2c1/0x3a0 kernel/kthread.c:389
> > >  ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
> > >  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> > > ...
> > >
> > > Freed by task 5245:
> > >  kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
> > >  kasan_save_track+0x14/0x30 mm/kasan/common.c:68
> > >  kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579
> > >  poison_slab_object+0xf7/0x160 mm/kasan/common.c:240
> > >  __kasan_slab_free+0x32/0x50 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+0x12a/0x3b0 mm/slub.c:4598
> > >  l2cap_conn_free net/bluetooth/l2cap_core.c:1810 [inline]
> > >  kref_put include/linux/kref.h:65 [inline]
> > >  l2cap_conn_put net/bluetooth/l2cap_core.c:1822 [inline]
> > >  l2cap_conn_del+0x59d/0x730 net/bluetooth/l2cap_core.c:1802
> > >  l2cap_connect_cfm+0x9e6/0xf80 net/bluetooth/l2cap_core.c:7241
> > >  hci_connect_cfm include/net/bluetooth/hci_core.h:1960 [inline]
> > >  hci_conn_failed+0x1c3/0x370 net/bluetooth/hci_conn.c:1265
> > >  hci_abort_conn_sync+0x75a/0xb50 net/bluetooth/hci_sync.c:5583
> > >  abort_conn_sync+0x197/0x360 net/bluetooth/hci_conn.c:2917
> > >  hci_cmd_sync_work+0x1a4/0x410 net/bluetooth/hci_sync.c:328
> > >  process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
> > >  process_scheduled_works kernel/workqueue.c:3312 [inline]
> > >  worker_thread+0x6c8/0xed0 kernel/workqueue.c:3389
> > >  kthread+0x2c1/0x3a0 kernel/kthread.c:389
> > >  ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
> > >  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> > >
> > > [Analysis]
> > > There was a data race when accessing conn in hci_rx_work and hci_cmd_sync_work.
> > > This is because the hci dev lock was prematurely exited when executing
> > > hci_acldata_macket() in hci_rx_work, which resulted in it being released
> > > by hci_cmd_sync_work when accessing conn outside the lock.
> > >
> > > Reported-and-tested-by: syzbot+c12e2f941af1feb5632c@syzkaller.appspotmail.com
> > > Closes: https://syzkaller.appspot.com/bug?extid=c12e2f941af1feb5632c
> > > Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> > > ---
> > >  net/bluetooth/hci_core.c   | 3 ++-
> > >  net/bluetooth/l2cap_core.c | 2 --
> > >  2 files changed, 2 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> > > index f25a21f532aa..4f7b45bb863f 100644
> > > --- a/net/bluetooth/hci_core.c
> > > +++ b/net/bluetooth/hci_core.c
> > > @@ -3776,18 +3776,19 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
> > >
> > >         hci_dev_lock(hdev);
> > >         conn = hci_conn_hash_lookup_handle(hdev, handle);
> > > -       hci_dev_unlock(hdev);
> > >
> > >         if (conn) {
> > >                 hci_conn_enter_active_mode(conn, BT_POWER_FORCE_ACTIVE_OFF);
> > >
> > >                 /* Send to upper protocol */
> > >                 l2cap_recv_acldata(conn, skb, flags);
> > > +               hci_dev_unlock(hdev);
> > >                 return;
> > >         } else {
> > >                 bt_dev_err(hdev, "ACL packet for unknown connection handle %d",
> > >                            handle);
> > >         }
> > > +       hci_dev_unlock(hdev);
> >
> > This is sort of risky, we shouldn't be calling this deep into the
> > stack with hci_dev_lock held.
I haven't thought of any better way yet. I understand what you mean, holding
hci_dev_lock for a long time.
At present, it is not impossible to try some strong drugs.
> >
> > >
> > >         kfree_skb(skb);
> > >  }
> > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> > > index 9988ba382b68..b948b0a3b2f2 100644
> > > --- a/net/bluetooth/l2cap_core.c
> > > +++ b/net/bluetooth/l2cap_core.c
> > > @@ -4072,10 +4072,8 @@ static int l2cap_connect_req(struct l2cap_conn *conn,
> > >         if (cmd_len < sizeof(struct l2cap_conn_req))
> > >                 return -EPROTO;
> > >
> > > -       hci_dev_lock(hdev);
> > >         if (hci_dev_test_flag(hdev, HCI_MGMT))
> > >                 mgmt_device_connected(hdev, hcon, NULL, 0);
> > > -       hci_dev_unlock(hdev);
> >
> > So this might explain why things gets freed while processing the
> > request, we are locking to call mgmt_device_connected which I suspect
> > is no longer needed ever since:
> >
> > commit db11223571d489d1aab575a4ac4b7352d2d54e2f
> > Author: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> > Date:   Tue Oct 25 14:12:58 2022 -0700
> >
> >     Bluetooth: btusb: Default CONFIG_BT_HCIBTUSB_POLL_SYNC=y
> >
> >     poll_sync has been proven to fix races of USB data and event endpoints
> >     so this enables it by default.
> >
> >     Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
> >     Tested-by: Tedd Ho-Jeong An <tedd.an@intel.com>
> >
> > Anyway syzbot don't use btusb so I think this might be due some
> > command pending that the emulator is not responding and instead
> > sending data, and then there is the issue that 7b064edae38d
> > ("Bluetooth: Fix authentication if acl data comes before remote
> > feature evt") attempted to fix which I think it actually made it worse
> > by moving the call to mgmt_device_connected into l2cap_core.c it sort
> > move the problem but didn't fix the actual problem.
I think 7B064edae38d is used to solve another issue.
> >
> > Maybe something like the following would be a better approach:
> >
> > https://gist.github.com/Vudentz/121a15fa4391b2b1f6c7e8d420a6846e
> 
> Any comments? Are you still planning to work on this?
Sorry for late.
> 
> > >
> > >         l2cap_connect(conn, cmd, data, L2CAP_CONN_RSP);
> > >         return 0;
> > > --
> > > 2.43.0
> > >
> >
> >
> > --
> > Luiz Augusto von Dentz

BR,
Edward

Re: [PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Hillf Danton]

On Tue, Sep 10, 2024 at 4:56 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
>
> Maybe something like the following would be a better approach:
>
> https://gist.github.com/Vudentz/121a15fa4391b2b1f6c7e8d420a6846e

If your idea is not bad, boy, feel free to win Tested-by from syzbot with it.

Re: [PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Luiz Augusto von Dentz]

Hi Hillf,

On Sat, Sep 21, 2024 at 6:56 AM Hillf Danton <hdanton@sina.com> wrote:
>
> On Tue, Sep 10, 2024 at 4:56 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> >
> > Maybe something like the following would be a better approach:
> >
> > https://gist.github.com/Vudentz/121a15fa4391b2b1f6c7e8d420a6846e
>
> If your idea is not bad, boy, feel free to win Tested-by from syzbot with it.

Is there a way to quickly check a patch with syzbot?

-- 
Luiz Augusto von Dentz

Re: [PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Aleksandr Nogikh]

On Mon, Sep 23, 2024 at 4:33 PM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Hillf,
>
> On Sat, Sep 21, 2024 at 6:56 AM Hillf Danton <hdanton@sina.com> wrote:
> >
> > On Tue, Sep 10, 2024 at 4:56 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> > >
> > > Maybe something like the following would be a better approach:
> > >
> > > https://gist.github.com/Vudentz/121a15fa4391b2b1f6c7e8d420a6846e
> >
> > If your idea is not bad, boy, feel free to win Tested-by from syzbot with it.
>
> Is there a way to quickly check a patch with syzbot?

You can send a `#syz test` command in a reply to syzbot and attach the
patch-to-test to the email message.

See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches

-- 
Aleksandr

>
> --
> Luiz Augusto von Dentz
>

Re: [PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Luiz Augusto von Dentz]

Hi Aleksandr,

On Mon, Sep 23, 2024 at 10:37 AM Aleksandr Nogikh <nogikh@google.com> wrote:
>
> On Mon, Sep 23, 2024 at 4:33 PM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> >
> > Hi Hillf,
> >
> > On Sat, Sep 21, 2024 at 6:56 AM Hillf Danton <hdanton@sina.com> wrote:
> > >
> > > On Tue, Sep 10, 2024 at 4:56 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> > > >
> > > > Maybe something like the following would be a better approach:
> > > >
> > > > https://gist.github.com/Vudentz/121a15fa4391b2b1f6c7e8d420a6846e
> > >
> > > If your idea is not bad, boy, feel free to win Tested-by from syzbot with it.
> >
> > Is there a way to quickly check a patch with syzbot?
>
> You can send a `#syz test` command in a reply to syzbot and attach the
> patch-to-test to the email message.
>
> See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches

Thanks, lets see if this works:

#syz test

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index d6976db02c06..b2f8f9c5b610 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3782,6 +3782,8 @@ static void hci_acldata_packet(struct hci_dev
*hdev, struct sk_buff *skb)

        hci_dev_lock(hdev);
        conn = hci_conn_hash_lookup_handle(hdev, handle);
+       if (conn && hci_dev_test_flag(hdev, HCI_MGMT))
+               mgmt_device_connected(hdev, conn, NULL, 0);
        hci_dev_unlock(hdev);

        if (conn) {
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 1c82dcdf6e8f..b87c0f1dab9e 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3706,7 +3706,7 @@ static void hci_remote_features_evt(struct
hci_dev *hdev, void *data,
                goto unlock;
        }

-       if (!ev->status && !test_bit(HCI_CONN_MGMT_CONNECTED, &conn->flags)) {
+       if (!ev->status) {
                struct hci_cp_remote_name_req cp;
                memset(&cp, 0, sizeof(cp));
                bacpy(&cp.bdaddr, &conn->dst);
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 9988ba382b68..6544c1ed7143 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4066,17 +4066,9 @@ static void l2cap_connect(struct l2cap_conn
*conn, struct l2cap_cmd_hdr *cmd,
 static int l2cap_connect_req(struct l2cap_conn *conn,
                             struct l2cap_cmd_hdr *cmd, u16 cmd_len, u8 *data)
 {
-       struct hci_dev *hdev = conn->hcon->hdev;
-       struct hci_conn *hcon = conn->hcon;
-
        if (cmd_len < sizeof(struct l2cap_conn_req))
                return -EPROTO;

-       hci_dev_lock(hdev);
-       if (hci_dev_test_flag(hdev, HCI_MGMT))
-               mgmt_device_connected(hdev, hcon, NULL, 0);
-       hci_dev_unlock(hdev);
-
        l2cap_connect(conn, cmd, data, L2CAP_CONN_RSP);
        return 0;
 }

Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_connect (2)

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to apply patch:
checking file net/bluetooth/hci_core.c
patch: **** malformed patch at line 6: diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c




Tested on:

commit:         de5cb0dc Merge branch 'address-masking'
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=57042fe37c7ee7c2
dashboard link: https://syzkaller.appspot.com/bug?extid=c12e2f941af1feb5632c
compiler:       
patch:          https://syzkaller.appspot.com/x/patch.diff?x=127c12a9980000

Re: [PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Aleksandr Nogikh]

Hi Luiz,

On Mon, Sep 23, 2024 at 5:20 PM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Aleksandr,
>
> On Mon, Sep 23, 2024 at 10:37 AM Aleksandr Nogikh <nogikh@google.com> wrote:
> >
> > On Mon, Sep 23, 2024 at 4:33 PM Luiz Augusto von Dentz
> > <luiz.dentz@gmail.com> wrote:
> > >
> > > Hi Hillf,
> > >
> > > On Sat, Sep 21, 2024 at 6:56 AM Hillf Danton <hdanton@sina.com> wrote:
> > > >
> > > > On Tue, Sep 10, 2024 at 4:56 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> > > > >
> > > > > Maybe something like the following would be a better approach:
> > > > >
> > > > > https://gist.github.com/Vudentz/121a15fa4391b2b1f6c7e8d420a6846e
> > > >
> > > > If your idea is not bad, boy, feel free to win Tested-by from syzbot with it.
> > >
> > > Is there a way to quickly check a patch with syzbot?
> >
> > You can send a `#syz test` command in a reply to syzbot and attach the
> > patch-to-test to the email message.
> >
> > See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches
>
> Thanks, lets see if this works:
>
> #syz test
>
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index d6976db02c06..b2f8f9c5b610 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -3782,6 +3782,8 @@ static void hci_acldata_packet(struct hci_dev
> *hdev, struct sk_buff *skb)
>
>         hci_dev_lock(hdev);
>         conn = hci_conn_hash_lookup_handle(hdev, handle);
> +       if (conn && hci_dev_test_flag(hdev, HCI_MGMT))
> +               mgmt_device_connected(hdev, conn, NULL, 0);
>         hci_dev_unlock(hdev);
>

^^ Patch parsing will fail here because it expects to see the git diff
output as is -- i.e. if some line only consisted of a single
whitespace (= it was an empty line and it did not change), it must
remain so. Sometimes these whitespaces get lost during copy-pasting
and it confuses syzbot.

>         if (conn) {
> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> index 1c82dcdf6e8f..b87c0f1dab9e 100644
> --- a/net/bluetooth/hci_event.c
> +++ b/net/bluetooth/hci_event.c
> @@ -3706,7 +3706,7 @@ static void hci_remote_features_evt(struct
> hci_dev *hdev, void *data,
>                 goto unlock;
>         }
>
> -       if (!ev->status && !test_bit(HCI_CONN_MGMT_CONNECTED, &conn->flags)) {
> +       if (!ev->status) {
>                 struct hci_cp_remote_name_req cp;
>                 memset(&cp, 0, sizeof(cp));
>                 bacpy(&cp.bdaddr, &conn->dst);
> diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> index 9988ba382b68..6544c1ed7143 100644
> --- a/net/bluetooth/l2cap_core.c
> +++ b/net/bluetooth/l2cap_core.c
> @@ -4066,17 +4066,9 @@ static void l2cap_connect(struct l2cap_conn
> *conn, struct l2cap_cmd_hdr *cmd,
>  static int l2cap_connect_req(struct l2cap_conn *conn,
>                              struct l2cap_cmd_hdr *cmd, u16 cmd_len, u8 *data)
>  {
> -       struct hci_dev *hdev = conn->hcon->hdev;
> -       struct hci_conn *hcon = conn->hcon;
> -
>         if (cmd_len < sizeof(struct l2cap_conn_req))
>                 return -EPROTO;
>
> -       hci_dev_lock(hdev);
> -       if (hci_dev_test_flag(hdev, HCI_MGMT))
> -               mgmt_device_connected(hdev, hcon, NULL, 0);
> -       hci_dev_unlock(hdev);
> -
>         l2cap_connect(conn, cmd, data, L2CAP_CONN_RSP);
>         return 0;
>  }

-- 
Aleksandr

Re: [PATCH] Bluetooth/l2cap: Fix uaf in l2cap_connect

[Luiz Augusto von Dentz]

Hi,

On Mon, Sep 23, 2024 at 11:20 AM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Aleksandr,
>
> On Mon, Sep 23, 2024 at 10:37 AM Aleksandr Nogikh <nogikh@google.com> wrote:
> >
> > On Mon, Sep 23, 2024 at 4:33 PM Luiz Augusto von Dentz
> > <luiz.dentz@gmail.com> wrote:
> > >
> > > Hi Hillf,
> > >
> > > On Sat, Sep 21, 2024 at 6:56 AM Hillf Danton <hdanton@sina.com> wrote:
> > > >
> > > > On Tue, Sep 10, 2024 at 4:56 PM Luiz Augusto von Dentz <luiz.dentz@gmail.com> wrote:
> > > > >
> > > > > Maybe something like the following would be a better approach:
> > > > >
> > > > > https://gist.github.com/Vudentz/121a15fa4391b2b1f6c7e8d420a6846e
> > > >
> > > > If your idea is not bad, boy, feel free to win Tested-by from syzbot with it.
> > >
> > > Is there a way to quickly check a patch with syzbot?
> >
> > You can send a `#syz test` command in a reply to syzbot and attach the
> > patch-to-test to the email message.
> >
> > See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patches
>

Lets try again with git diff output:

#syz test

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index d6976db02c06..b2f8f9c5b610 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3782,6 +3782,8 @@ static void hci_acldata_packet(struct hci_dev
*hdev, struct sk_buff *skb)

     hci_dev_lock(hdev);
     conn = hci_conn_hash_lookup_handle(hdev, handle);
+    if (conn && hci_dev_test_flag(hdev, HCI_MGMT))
+        mgmt_device_connected(hdev, conn, NULL, 0);
     hci_dev_unlock(hdev);

     if (conn) {
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 1c82dcdf6e8f..b87c0f1dab9e 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -3706,7 +3706,7 @@ static void hci_remote_features_evt(struct
hci_dev *hdev, void *data,
         goto unlock;
     }

-    if (!ev->status && !test_bit(HCI_CONN_MGMT_CONNECTED, &conn->flags)) {
+    if (!ev->status) {
         struct hci_cp_remote_name_req cp;
         memset(&cp, 0, sizeof(cp));
         bacpy(&cp.bdaddr, &conn->dst);
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 9988ba382b68..6544c1ed7143 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4066,17 +4066,9 @@ static void l2cap_connect(struct l2cap_conn
*conn, struct l2cap_cmd_hdr *cmd,
 static int l2cap_connect_req(struct l2cap_conn *conn,
                  struct l2cap_cmd_hdr *cmd, u16 cmd_len, u8 *data)
 {
-    struct hci_dev *hdev = conn->hcon->hdev;
-    struct hci_conn *hcon = conn->hcon;
-
     if (cmd_len < sizeof(struct l2cap_conn_req))
         return -EPROTO;

-    hci_dev_lock(hdev);
-    if (hci_dev_test_flag(hdev, HCI_MGMT))
-        mgmt_device_connected(hdev, hcon, NULL, 0);
-    hci_dev_unlock(hdev);
-
     l2cap_connect(conn, cmd, data, L2CAP_CONN_RSP);
     return 0;
 }

Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_connect (2)

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to apply patch:
checking file net/bluetooth/hci_core.c
patch: **** malformed patch at line 6: diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c




Tested on:

commit:         de5cb0dc Merge branch 'address-masking'
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=57042fe37c7ee7c2
dashboard link: https://syzkaller.appspot.com/bug?extid=c12e2f941af1feb5632c
compiler:       
patch:          https://syzkaller.appspot.com/x/patch.diff?x=11f72107980000