f9c70bdc27
In the case we set or free the global value listen_chan in different threads, we can encounter the UAF problems because the method is not protected by any lock, add one to avoid this bug. BUG: KASAN: use-after-free in l2cap_chan_close+0x48/0x990 net/bluetooth/l2cap_core.c:730 Read of size 8 at addr ffff888096950000 by task kworker/1:102/2868 CPU: 1 PID: 2868 Comm: kworker/1:102 Not tainted 5.5.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events do_enable_set Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1fb/0x318 lib/dump_stack.c:118 print_address_description+0x74/0x5c0 mm/kasan/report.c:374 __kasan_report+0x149/0x1c0 mm/kasan/report.c:506 kasan_report+0x26/0x50 mm/kasan/common.c:641 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135 l2cap_chan_close+0x48/0x990 net/bluetooth/l2cap_core.c:730 do_enable_set+0x660/0x900 net/bluetooth/6lowpan.c:1074 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Allocated by task 2870: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc+0x118/0x1c0 mm/kasan/common.c:515 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 kmem_cache_alloc_trace+0x221/0x2f0 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] l2cap_chan_create+0x50/0x320 net/bluetooth/l2cap_core.c:446 chan_create net/bluetooth/6lowpan.c:640 [inline] bt_6lowpan_listen net/bluetooth/6lowpan.c:959 [inline] do_enable_set+0x6a4/0x900 net/bluetooth/6lowpan.c:1078 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Freed by task 2870: save_stack mm/kasan/common.c:72 [inline] set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x12e/0x1e0 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x10d/0x220 mm/slab.c:3757 l2cap_chan_destroy net/bluetooth/l2cap_core.c:484 [inline] kref_put include/linux/kref.h:65 [inline] l2cap_chan_put+0x170/0x190 net/bluetooth/l2cap_core.c:498 do_enable_set+0x66c/0x900 net/bluetooth/6lowpan.c:1075 process_one_work+0x7f5/0x10f0 kernel/workqueue.c:2264 worker_thread+0xbbc/0x1630 kernel/workqueue.c:2410 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 The buggy address belongs to the object at ffff888096950000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 0 bytes inside of 2048-byte region [ffff888096950000, ffff888096950800) The buggy address belongs to the page: page:ffffea00025a5400 refcount:1 mapcount:0 mapping:ffff8880aa400e00 index:0x0 flags: 0xfffe0000000200(slab) raw: 00fffe0000000200 ffffea00027d1548 ffffea0002397808 ffff8880aa400e00 raw: 0000000000000000 ffff888096950000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809694ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88809694ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888096950000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888096950080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888096950100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Reported-by: syzbot+96414aa0033c363d8458@syzkaller.appspotmail.com Signed-off-by: Lihong Kou <koulihong@huawei.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.