https://bugzilla.kernel.org/show_bug.cgi?id=218440 Bug ID: 218440 Summary: KASAN: slab-use-after-free in hci_send_acl in Kernel 6.7-rc2 Product: Drivers Version: 2.5 Hardware: All OS: Linux Status: NEW Severity: high Priority: P3 Component: Bluetooth Assignee: linux-bluetooth@xxxxxxxxxxxxxxx Reporter: zhenghaoran@xxxxxxxxxxx Regression: No Hello, I am writing to report a potential use-after-free that our fuzzing tool found in the 'hci_send_acl' function. The bug was encountered while testing kernel 6.7-rc2 during a Bluetooth pairing procedure. Due to the non-determinism of concurrent execution, this bug cannot be stably reproduced in my testing. Through disassembly, we have pinpointed the code at 'hci_send_acl+0x54', which corresponds to the function 'hci_send_acl', specifically at the line: File: net/bluetooth/hci_core.c Line: 3234 struct hci_dev *hdev = chan->conn->hdev; Based on the allocate and free tasks reported by KASAN, we suspect that the use-after-free issue originates from the 'chan' variable in the parameter passed into the 'hci_send_acl' function. Although the 'l2cap_conn conn' variable and 'l2cap_chan conn->chan' variable are locked in the 'l2cap_conn_start' function, 'hci_chan conn->hchan' may still be released by other threads, causing a use-after-free vulnerability. This appears to be a very subtle timing issue, which may explain the difficulty we have had in reproducing the bug. KASAN report： ================================================================== BUG: KASAN: slab-use-after-free in hci_send_acl+0x54/0x770 [bluetooth] Read of size 8 at addr ffff888007212618 by task kworker/0:0/688 CPU: 0 PID: 688 Comm: kworker/0:0 Tainted: G O 6.7.0-rc2 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Workqueue: events l2cap_info_timeout [bluetooth] Call Trace: <TASK> dump_stack_lvl+0xbf/0xf0 print_address_description+0x7f/0x3d0 print_report+0x11d/0x250 ? __virt_addr_valid+0xc5/0xf0 ? hci_send_acl+0x54/0x770 [bluetooth] kasan_report+0x137/0x170 ? hci_send_acl+0x54/0x770 [bluetooth] hci_send_acl+0x54/0x770 [bluetooth] ? get_thread_local+0x9d/0x140 [mfuzz_monitor] l2cap_send_cmd+0x633/0xa40 [bluetooth] l2cap_send_conn_req+0x1ad/0x360 [bluetooth] l2cap_start_connection+0x178/0x420 [bluetooth] l2cap_conn_start+0x94e/0xdc0 [bluetooth] ? get_thread_local+0x9d/0x140 [mfuzz_monitor] ? __mfuzz_coverage__+0x16/0x140 [mfuzz_monitor] process_one_work+0x4f0/0xab0 worker_thread+0x8af/0xee0 ? _raw_spin_lock_irqsave+0x8d/0x130 ? process_one_work+0xab0/0xab0 kthread+0x275/0x300 ? process_one_work+0xab0/0xab0 ? kthread_blkcg+0xa0/0xa0 ret_from_fork+0x30/0x60 ? kthread_blkcg+0xa0/0xa0 ret_from_fork_asm+0x11/0x20 </TASK> Allocated by task 1167: kasan_set_track+0x4c/0x70 __kasan_kmalloc+0x82/0x90 __kmalloc+0xac/0x1d0 hci_chan_create+0x92/0x1c0 [bluetooth] l2cap_conn_add+0x8f/0xe30 [bluetooth] l2cap_chan_connect+0x5b4/0xff0 [bluetooth] l2cap_sock_connect+0x420/0x890 [bluetooth] kernel_connect+0xb3/0xe0 rfcomm_dlc_open+0x605/0x1190 [rfcomm] rfcomm_sock_connect+0x3c4/0x7f0 [rfcomm] __sys_connect+0x20f/0x270 __x64_sys_connect+0x71/0x80 do_syscall_64+0x32/0xa0 entry_SYSCALL_64_after_hwframe+0x63/0x6b Freed by task 1155: kasan_set_track+0x4c/0x70 kasan_save_free_info+0x24/0x40 ____kasan_slab_free+0x118/0x190 slab_free_freelist_hook+0xd1/0x160 __kmem_cache_free+0xa3/0x170 hci_chan_list_flush+0x85/0xc0 [bluetooth] hci_conn_del+0x568/0x1010 [bluetooth] hci_abort_conn_sync+0x7d9/0xaf0 [bluetooth] abort_conn_sync+0x78/0xd0 [bluetooth] hci_cmd_sync_work+0x1f7/0x2b0 [bluetooth] process_one_work+0x4f0/0xab0 worker_thread+0x8af/0xee0 kthread+0x275/0x300 ret_from_fork+0x30/0x60 ret_from_fork_asm+0x11/0x20 The buggy address belongs to the object at ffff888007212600 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 24 bytes inside of freed 64-byte region [ffff888007212600, ffff888007212640) The buggy address belongs to the physical page: page:00000000baf0b98e refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7212 anon flags: 0x100000000000800(slab|node=0|zone=1) page_type: 0xffffffff() raw: 0100000000000800 ffff888001041640 ffffea0000079d40 dead000000000003 raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888007212500: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc ffff888007212580: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff888007212600: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ^ ffff888007212680: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff888007212700: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ================================================================== -- You may reply to this email to add a comment. You are receiving this mail because: You are the assignee for the bug.
