On 28/11/2022 11:07, Dmitry Vyukov wrote: > On Sun, 27 Nov 2022 at 20:59, Krzysztof Kozlowski > <krzysztof.kozlowski@xxxxxxxxxx> wrote: >> >> On 25/11/2022 10:09, Johannes Berg wrote: >>> Looks like an NFC issue to me, Krzysztof? >>> >>> I mean, rfkill got allocated by nfc_register_device(), freed by >>> nfc_unregister_device(), and then used by nfc_dev_up(). Seems like the >>> last bit shouldn't be possible after nfc_unregister_device()? >>> >>> johannes >>> >>> On Wed, 2022-11-23 at 22:24 -0800, syzbot wrote: >>>> Hello, >>>> >>>> syzbot found the following issue on: >>>> >>>> HEAD commit: 0966d385830d riscv: Fix auipc+jalr relocation range checks >>>> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes >>>> console output: https://syzkaller.appspot.com/x/log.txt?x=11196d0d880000 >>>> kernel config: https://syzkaller.appspot.com/x/.config?x=6295d67591064921 >>>> dashboard link: https://syzkaller.appspot.com/bug?extid=0299462c067009827b2a >>>> compiler: riscv64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 >>>> userspace arch: riscv64 >>>> >>>> Unfortunately, I don't have any reproducer for this issue yet. >>>> >>>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>>> Reported-by: syzbot+0299462c067009827b2a@xxxxxxxxxxxxxxxxxxxxxxxxx >>>> >>>> ================================================================== >>>> BUG: KASAN: use-after-free in __lock_acquire+0x8ee/0x333e kernel/locking/lockdep.c:4897 >>>> Read of size 8 at addr ffffaf8024249018 by task syz-executor.0/7946 >>>> >>>> CPU: 0 PID: 7946 Comm: syz-executor.0 Not tainted 5.17.0-rc1-syzkaller-00002-g0966d385830d #0 >>>> Hardware name: riscv-virtio,qemu (DT) >>>> Call Trace: >>>> [<ffffffff8000a228>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:113 >>>> [<ffffffff831668cc>] show_stack+0x34/0x40 arch/riscv/kernel/stacktrace.c:119 >>>> [<ffffffff831756ba>] __dump_stack lib/dump_stack.c:88 [inline] >>>> [<ffffffff831756ba>] dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:106 >>>> [<ffffffff8047479e>] print_address_description.constprop.0+0x2a/0x330 mm/kasan/report.c:255 >>>> [<ffffffff80474d4c>] __kasan_report mm/kasan/report.c:442 [inline] >>>> [<ffffffff80474d4c>] kasan_report+0x184/0x1e0 mm/kasan/report.c:459 >>>> [<ffffffff80475b20>] check_region_inline mm/kasan/generic.c:183 [inline] >>>> [<ffffffff80475b20>] __asan_load8+0x6e/0x96 mm/kasan/generic.c:256 >>>> [<ffffffff80112b70>] __lock_acquire+0x8ee/0x333e kernel/locking/lockdep.c:4897 >>>> [<ffffffff80116582>] lock_acquire.part.0+0x1d0/0x424 kernel/locking/lockdep.c:5639 >>>> [<ffffffff8011682a>] lock_acquire+0x54/0x6a kernel/locking/lockdep.c:5612 >>>> [<ffffffff831afa2c>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] >>>> [<ffffffff831afa2c>] _raw_spin_lock_irqsave+0x3e/0x62 kernel/locking/spinlock.c:162 >>>> [<ffffffff83034f0a>] rfkill_blocked+0x22/0x62 net/rfkill/core.c:941 >>>> [<ffffffff830b8862>] nfc_dev_up+0x8e/0x26c net/nfc/core.c:102 >>>> [<ffffffff830bb742>] nfc_genl_dev_up+0x5e/0x8a net/nfc/netlink.c:770 >>>> [<ffffffff8296f9ae>] genl_family_rcv_msg_doit+0x19a/0x23c net/netlink/genetlink.c:731 >>>> [<ffffffff82970420>] genl_family_rcv_msg net/netlink/genetlink.c:775 [inline] >>>> [<ffffffff82970420>] genl_rcv_msg+0x236/0x3ba net/netlink/genetlink.c:792 >>>> [<ffffffff8296ded2>] netlink_rcv_skb+0xf8/0x2be net/netlink/af_netlink.c:2494 >>>> [<ffffffff8296ecb2>] genl_rcv+0x36/0x4c net/netlink/genetlink.c:803 >>>> [<ffffffff8296cbcc>] netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline] >>>> [<ffffffff8296cbcc>] netlink_unicast+0x40e/0x5fe net/netlink/af_netlink.c:1343 >>>> [<ffffffff8296d29c>] netlink_sendmsg+0x4e0/0x994 net/netlink/af_netlink.c:1919 >>>> [<ffffffff826d264e>] sock_sendmsg_nosec net/socket.c:705 [inline] >>>> [<ffffffff826d264e>] sock_sendmsg+0xa0/0xc4 net/socket.c:725 >>>> [<ffffffff826d4dd4>] ____sys_sendmsg+0x46e/0x484 net/socket.c:2413 >>>> [<ffffffff826d8bca>] ___sys_sendmsg+0x16c/0x1f6 net/socket.c:2467 >>>> [<ffffffff826d8e78>] __sys_sendmsg+0xba/0x150 net/socket.c:2496 >>>> [<ffffffff826d8f3a>] __do_sys_sendmsg net/socket.c:2505 [inline] >>>> [<ffffffff826d8f3a>] sys_sendmsg+0x2c/0x3a net/socket.c:2503 >>>> [<ffffffff80005716>] ret_from_syscall+0x0/0x2 >>>> >>>> Allocated by task 7946: >>>> stack_trace_save+0xa6/0xd8 kernel/stacktrace.c:122 >>>> kasan_save_stack+0x2c/0x58 mm/kasan/common.c:38 >>>> kasan_set_track mm/kasan/common.c:45 [inline] >>>> set_alloc_info mm/kasan/common.c:436 [inline] >>>> ____kasan_kmalloc mm/kasan/common.c:515 [inline] >>>> ____kasan_kmalloc mm/kasan/common.c:474 [inline] >>>> __kasan_kmalloc+0x80/0xb2 mm/kasan/common.c:524 >>>> kasan_kmalloc include/linux/kasan.h:270 [inline] >>>> __kmalloc+0x190/0x318 mm/slub.c:4424 >>>> kmalloc include/linux/slab.h:586 [inline] >>>> kzalloc include/linux/slab.h:715 [inline] >>>> rfkill_alloc+0x96/0x1aa net/rfkill/core.c:983 >>>> nfc_register_device+0xe4/0x29e net/nfc/core.c:1129 >>>> nci_register_device+0x538/0x612 net/nfc/nci/core.c:1252 >>>> virtual_ncidev_open+0x82/0x12c drivers/nfc/virtual_ncidev.c:143 >>>> misc_open+0x272/0x2c8 drivers/char/misc.c:141 >>>> chrdev_open+0x1d4/0x478 fs/char_dev.c:414 >>>> do_dentry_open+0x2a4/0x7d4 fs/open.c:824 >>>> vfs_open+0x52/0x5e fs/open.c:959 >>>> do_open fs/namei.c:3476 [inline] >>>> path_openat+0x12b6/0x189e fs/namei.c:3609 >>>> do_filp_open+0x10e/0x22a fs/namei.c:3636 >>>> do_sys_openat2+0x174/0x31e fs/open.c:1214 >>>> do_sys_open fs/open.c:1230 [inline] >>>> __do_sys_openat fs/open.c:1246 [inline] >>>> sys_openat+0xdc/0x164 fs/open.c:1241 >>>> ret_from_syscall+0x0/0x2 >>>> >>>> Freed by task 7944: >>>> stack_trace_save+0xa6/0xd8 kernel/stacktrace.c:122 >>>> kasan_save_stack+0x2c/0x58 mm/kasan/common.c:38 >>>> kasan_set_track+0x1a/0x26 mm/kasan/common.c:45 >>>> kasan_set_free_info+0x1e/0x3a mm/kasan/generic.c:370 >>>> ____kasan_slab_free mm/kasan/common.c:366 [inline] >>>> ____kasan_slab_free+0x15e/0x180 mm/kasan/common.c:328 >>>> __kasan_slab_free+0x10/0x18 mm/kasan/common.c:374 >>>> kasan_slab_free include/linux/kasan.h:236 [inline] >>>> slab_free_hook mm/slub.c:1728 [inline] >>>> slab_free_freelist_hook+0x8e/0x1cc mm/slub.c:1754 >>>> slab_free mm/slub.c:3509 [inline] >>>> kfree+0xe0/0x3e4 mm/slub.c:4562 >>>> rfkill_release+0x20/0x2a net/rfkill/core.c:831 >>>> device_release+0x66/0x148 drivers/base/core.c:2229 >>>> kobject_cleanup lib/kobject.c:705 [inline] >>>> kobject_release lib/kobject.c:736 [inline] >>>> kref_put include/linux/kref.h:65 [inline] >>>> kobject_put+0x1bc/0x38e lib/kobject.c:753 >>>> put_device+0x28/0x3a drivers/base/core.c:3512 >>>> rfkill_destroy+0x2a/0x3c net/rfkill/core.c:1142 >>>> nfc_unregister_device+0xac/0x232 net/nfc/core.c:1167 >>>> nci_unregister_device+0x168/0x182 net/nfc/nci/core.c:1298 >>>> virtual_ncidev_close+0x9c/0xbc drivers/nfc/virtual_ncidev.c:163 >> >> There were several issues found recently in virtual NCI driver, so this >> might be one of them. There is no reproducer, though... > > > Hi Krzysztof, > > Do you think it's related specifically to the virtual driver? Both, although maybe not this particular issue. There were like five separate reports last few days... > > I would assume it's a bug in the NCI core itself related to dynamic > device destructions. This should affect e.g. USB devices as well. Earlier this year there was a bigger fix for unregister path in NFC - see commits: da5c0f119203 (nfc_unregister_device+nfc_fw_download ef27324e2c (nci_unregister_device+nci_cmd_work) 1b0e81416 (rfkill related) and these pointed out inherent issues in locking/synchronization of NFC core modules. I don't think we fixed all of the core issues, rather only what was reported, so some specific scenarios. > It's an issue only in the virtual driver. It means that the virtual > driver uses the NCI core incorrectly, not the way all real drivers use > it. If so the question is: what is the difference? We need to fix it. > It's not useful to have unrealistic test drivers -- we both get false > positives and don't get true positives. > > I think the issue may be localized from the KASAN report itself w/o a > reproducer. > Is there proper synchronization between > nfc_unregister_device/rfkill_destroy and nfc_dev_up/rfkill_blocked? > Something that prevents rfkill_blocked to be called after > rfkill_destroy? If not, then that's the issue. Mentioned 1b0e81416a tried to do this and that time I had impression fix is correct. However it seems it is not... (or not enough) Best regards, Krzysztof
