8c36e66fb4
In the error path for nvme_init_subsystem(), nvme_put_subsystem() will call device_put(), but it will get called again after the mutex_unlock(). The device_put() only needs to be called if device_add() fails. This bug caused a KASAN use-after-free error when adding and removing subsytems in a loop: BUG: KASAN: use-after-free in device_del+0x8d9/0x9a0 Read of size 8 at addr ffff8883cdaf7120 by task multipathd/329 CPU: 0 PID: 329 Comm: multipathd Not tainted 5.2.0-rc6-vmlocalyes-00019-g70a2b39005fd-dirty #314 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 Call Trace: dump_stack+0x7b/0xb5 print_address_description+0x6f/0x280 ? device_del+0x8d9/0x9a0 __kasan_report+0x148/0x199 ? device_del+0x8d9/0x9a0 ? class_release+0x100/0x130 ? device_del+0x8d9/0x9a0 kasan_report+0x12/0x20 __asan_report_load8_noabort+0x14/0x20 device_del+0x8d9/0x9a0 ? device_platform_notify+0x70/0x70 nvme_destroy_subsystem+0xf9/0x150 nvme_free_ctrl+0x280/0x3a0 device_release+0x72/0x1d0 kobject_put+0x144/0x410 put_device+0x13/0x20 nvme_free_ns+0xc4/0x100 nvme_release+0xb3/0xe0 __blkdev_put+0x549/0x6e0 ? kasan_check_write+0x14/0x20 ? bd_set_size+0xb0/0xb0 ? kasan_check_write+0x14/0x20 ? mutex_lock+0x8f/0xe0 ? __mutex_lock_slowpath+0x20/0x20 ? locks_remove_file+0x239/0x370 blkdev_put+0x72/0x2c0 blkdev_close+0x8d/0xd0 __fput+0x256/0x770 ? _raw_read_lock_irq+0x40/0x40 ____fput+0xe/0x10 task_work_run+0x10c/0x180 ? filp_close+0xf7/0x140 exit_to_usermode_loop+0x151/0x170 do_syscall_64+0x240/0x2e0 ? prepare_exit_to_usermode+0xd5/0x190 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f5a79af05d7 Code: 00 00 0f 05 48 3d 00 f0 ff ff 77 3f c3 66 0f 1f 44 00 00 53 89 fb 48 83 ec 10 e8 c4 fb ff ff 89 df 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 2b 89 d7 89 44 24 0c e8 06 fc ff ff 8b 44 24 RSP: 002b:00007f5a7799c810 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000008 RCX: 00007f5a79af05d7 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000008 RBP: 00007f5a58000f98 R08: 0000000000000002 R09: 00007f5a7935ee80 R10: 0000000000000000 R11: 0000000000000293 R12: 000055e432447240 R13: 0000000000000000 R14: 0000000000000001 R15: 000055e4324a9cf0 Allocated by task 1236: save_stack+0x21/0x80 __kasan_kmalloc.constprop.6+0xab/0xe0 kasan_kmalloc+0x9/0x10 kmem_cache_alloc_trace+0x102/0x210 nvme_init_identify+0x13c3/0x3820 nvme_loop_configure_admin_queue+0x4fa/0x5e0 nvme_loop_create_ctrl+0x469/0xf40 nvmf_dev_write+0x19a3/0x21ab __vfs_write+0x66/0x120 vfs_write+0x154/0x490 ksys_write+0x104/0x240 __x64_sys_write+0x73/0xb0 do_syscall_64+0xa5/0x2e0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 329: save_stack+0x21/0x80 __kasan_slab_free+0x129/0x190 kasan_slab_free+0xe/0x10 kfree+0xa7/0x200 nvme_release_subsystem+0x49/0x60 device_release+0x72/0x1d0 kobject_put+0x144/0x410 put_device+0x13/0x20 klist_class_dev_put+0x31/0x40 klist_put+0x8f/0xf0 klist_del+0xe/0x10 device_del+0x3a7/0x9a0 nvme_destroy_subsystem+0xf9/0x150 nvme_free_ctrl+0x280/0x3a0 device_release+0x72/0x1d0 kobject_put+0x144/0x410 put_device+0x13/0x20 nvme_free_ns+0xc4/0x100 nvme_release+0xb3/0xe0 __blkdev_put+0x549/0x6e0 blkdev_put+0x72/0x2c0 blkdev_close+0x8d/0xd0 __fput+0x256/0x770 ____fput+0xe/0x10 task_work_run+0x10c/0x180 exit_to_usermode_loop+0x151/0x170 do_syscall_64+0x240/0x2e0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: 32fd90c40768 ("nvme: change locking for the per-subsystem controller list") Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by : Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
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.