84205f964b
commit 1ff5325c3ca1843228a86549318bbd3b414b9207 upstream. Avoid circular locking dependency by calling to uobj_alloc_commit() outside of xrcd_tree_mutex lock. ====================================================== WARNING: possible circular locking dependency detected 4.15.0+ #87 Not tainted ------------------------------------------------------ syzkaller401056/269 is trying to acquire lock: (&uverbs_dev->xrcd_tree_mutex){+.+.}, at: [<000000006c12d2cd>] uverbs_free_xrcd+0xd2/0x360 but task is already holding lock: (&ucontext->uobjects_lock){+.+.}, at: [<00000000da010f09>] uverbs_cleanup_ucontext+0x168/0x730 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&ucontext->uobjects_lock){+.+.}: __mutex_lock+0x111/0x1720 rdma_alloc_commit_uobject+0x22c/0x600 ib_uverbs_open_xrcd+0x61a/0xdd0 ib_uverbs_write+0x7f9/0xef0 __vfs_write+0x10d/0x700 vfs_write+0x1b0/0x550 SyS_write+0xc7/0x1a0 entry_SYSCALL_64_fastpath+0x1e/0x8b -> #0 (&uverbs_dev->xrcd_tree_mutex){+.+.}: lock_acquire+0x19d/0x440 __mutex_lock+0x111/0x1720 uverbs_free_xrcd+0xd2/0x360 remove_commit_idr_uobject+0x6d/0x110 uverbs_cleanup_ucontext+0x2f0/0x730 ib_uverbs_cleanup_ucontext.constprop.3+0x52/0x120 ib_uverbs_close+0xf2/0x570 __fput+0x2cd/0x8d0 task_work_run+0xec/0x1d0 do_exit+0x6a1/0x1520 do_group_exit+0xe8/0x380 SyS_exit_group+0x1e/0x20 entry_SYSCALL_64_fastpath+0x1e/0x8b other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ucontext->uobjects_lock); lock(&uverbs_dev->xrcd_tree_mutex); lock(&ucontext->uobjects_lock); lock(&uverbs_dev->xrcd_tree_mutex); *** DEADLOCK *** 3 locks held by syzkaller401056/269: #0: (&file->cleanup_mutex){+.+.}, at: [<00000000c9f0c252>] ib_uverbs_close+0xac/0x570 #1: (&ucontext->cleanup_rwsem){++++}, at: [<00000000b6994d49>] uverbs_cleanup_ucontext+0xf6/0x730 #2: (&ucontext->uobjects_lock){+.+.}, at: [<00000000da010f09>] uverbs_cleanup_ucontext+0x168/0x730 stack backtrace: CPU: 0 PID: 269 Comm: syzkaller401056 Not tainted 4.15.0+ #87 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014 Call Trace: dump_stack+0xde/0x164 ? dma_virt_map_sg+0x22c/0x22c ? uverbs_cleanup_ucontext+0x168/0x730 ? console_unlock+0x502/0xbd0 print_circular_bug.isra.24+0x35e/0x396 ? print_circular_bug_header+0x12e/0x12e ? find_usage_backwards+0x30/0x30 ? entry_SYSCALL_64_fastpath+0x1e/0x8b validate_chain.isra.28+0x25d1/0x40c0 ? check_usage+0xb70/0xb70 ? graph_lock+0x160/0x160 ? find_usage_backwards+0x30/0x30 ? cyc2ns_read_end+0x10/0x10 ? print_irqtrace_events+0x280/0x280 ? __lock_acquire+0x93d/0x1630 __lock_acquire+0x93d/0x1630 lock_acquire+0x19d/0x440 ? uverbs_free_xrcd+0xd2/0x360 __mutex_lock+0x111/0x1720 ? uverbs_free_xrcd+0xd2/0x360 ? uverbs_free_xrcd+0xd2/0x360 ? __mutex_lock+0x828/0x1720 ? mutex_lock_io_nested+0x1550/0x1550 ? uverbs_cleanup_ucontext+0x168/0x730 ? __lock_acquire+0x9a9/0x1630 ? mutex_lock_io_nested+0x1550/0x1550 ? uverbs_cleanup_ucontext+0xf6/0x730 ? lock_contended+0x11a0/0x11a0 ? uverbs_free_xrcd+0xd2/0x360 uverbs_free_xrcd+0xd2/0x360 remove_commit_idr_uobject+0x6d/0x110 uverbs_cleanup_ucontext+0x2f0/0x730 ? sched_clock_cpu+0x18/0x200 ? uverbs_close_fd+0x1c0/0x1c0 ib_uverbs_cleanup_ucontext.constprop.3+0x52/0x120 ib_uverbs_close+0xf2/0x570 ? ib_uverbs_remove_one+0xb50/0xb50 ? ib_uverbs_remove_one+0xb50/0xb50 __fput+0x2cd/0x8d0 task_work_run+0xec/0x1d0 do_exit+0x6a1/0x1520 ? fsnotify_first_mark+0x220/0x220 ? exit_notify+0x9f0/0x9f0 ? entry_SYSCALL_64_fastpath+0x5/0x8b ? entry_SYSCALL_64_fastpath+0x5/0x8b ? trace_hardirqs_on_thunk+0x1a/0x1c ? time_hardirqs_on+0x27/0x670 ? time_hardirqs_off+0x27/0x490 ? syscall_return_slowpath+0x6c/0x460 ? entry_SYSCALL_64_fastpath+0x5/0x8b do_group_exit+0xe8/0x380 SyS_exit_group+0x1e/0x20 entry_SYSCALL_64_fastpath+0x1e/0x8b RIP: 0033:0x431ce9 Cc: syzkaller <syzkaller@googlegroups.com> Cc: <stable@vger.kernel.org> # 4.11 Fixes: fd3c7904db6e ("IB/core: Change idr objects to use the new schema") Reported-by: Noa Osherovich <noaos@mellanox.com> Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.