kernel.git/fs/aio.c, branch linux-4.20.y

aio: Fix locking in aio_poll()

2019-03-10T06:10:15Z

commit d3d6a18d7d351cbcc9b33dbedf710e65f8ce1595 upstream. wake_up_locked() may but does not have to be called with interrupts disabled. Since the fuse filesystem calls wake_up_locked() without disabling interrupts aio_poll_wake() may be called with interrupts enabled. Since the kioctx.ctx_lock may be acquired from IRQ context, all code that acquires that lock from thread context must disable interrupts. Hence change the spin_trylock() call in aio_poll_wake() into a spin_trylock_irqsave() call. This patch fixes the following lockdep complaint: ===================================================== WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected 5.0.0-rc4-next-20190131 #23 Not tainted ----------------------------------------------------- syz-executor2/13779 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: 0000000098ac1230 (&fiq->waitq){+.+.}, at: spin_lock include/linux/spinlock.h:329 [inline] 0000000098ac1230 (&fiq->waitq){+.+.}, at: aio_poll fs/aio.c:1772 [inline] 0000000098ac1230 (&fiq->waitq){+.+.}, at: __io_submit_one fs/aio.c:1875 [inline] 0000000098ac1230 (&fiq->waitq){+.+.}, at: io_submit_one+0xedf/0x1cf0 fs/aio.c:1908 and this task is already holding: 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:354 [inline] 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: aio_poll fs/aio.c:1771 [inline] 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: __io_submit_one fs/aio.c:1875 [inline] 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: io_submit_one+0xeb6/0x1cf0 fs/aio.c:1908 which would create a new lock dependency: (&(&ctx->ctx_lock)->rlock){..-.} -> (&fiq->waitq){+.+.} but this new dependency connects a SOFTIRQ-irq-safe lock: (&(&ctx->ctx_lock)->rlock){..-.} ... which became SOFTIRQ-irq-safe at: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:160 spin_lock_irq include/linux/spinlock.h:354 [inline] free_ioctx_users+0x2d/0x4a0 fs/aio.c:610 percpu_ref_put_many include/linux/percpu-refcount.h:285 [inline] percpu_ref_put include/linux/percpu-refcount.h:301 [inline] percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline] percpu_ref_switch_to_atomic_rcu+0x3e7/0x520 lib/percpu-refcount.c:158 __rcu_reclaim kernel/rcu/rcu.h:240 [inline] rcu_do_batch kernel/rcu/tree.c:2486 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2799 [inline] rcu_core+0x928/0x1390 kernel/rcu/tree.c:2780 __do_softirq+0x266/0x95a kernel/softirq.c:292 run_ksoftirqd kernel/softirq.c:654 [inline] run_ksoftirqd+0x8e/0x110 kernel/softirq.c:646 smpboot_thread_fn+0x6ab/0xa10 kernel/smpboot.c:164 kthread+0x357/0x430 kernel/kthread.c:247 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 to a SOFTIRQ-irq-unsafe lock: (&fiq->waitq){+.+.} ... which became SOFTIRQ-irq-unsafe at: ... lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415 fuse_request_queue_background+0x2d1/0x580 fs/fuse/dev.c:676 fuse_request_send_background+0x58/0x120 fs/fuse/dev.c:687 fuse_send_init fs/fuse/inode.c:989 [inline] fuse_fill_super+0x13bb/0x1730 fs/fuse/inode.c:1214 mount_nodev+0x68/0x110 fs/super.c:1392 fuse_mount+0x2d/0x40 fs/fuse/inode.c:1239 legacy_get_tree+0xf2/0x200 fs/fs_context.c:590 vfs_get_tree+0x123/0x450 fs/super.c:1481 do_new_mount fs/namespace.c:2610 [inline] do_mount+0x1436/0x2c40 fs/namespace.c:2932 ksys_mount+0xdb/0x150 fs/namespace.c:3148 __do_sys_mount fs/namespace.c:3162 [inline] __se_sys_mount fs/namespace.c:3159 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3159 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fiq->waitq); local_irq_disable(); lock(&(&ctx->ctx_lock)->rlock); lock(&fiq->waitq); lock(&(&ctx->ctx_lock)->rlock); *** DEADLOCK *** 1 lock held by syz-executor2/13779: #0: 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:354 [inline] #0: 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: aio_poll fs/aio.c:1771 [inline] #0: 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: __io_submit_one fs/aio.c:1875 [inline] #0: 000000003c46111c (&(&ctx->ctx_lock)->rlock){..-.}, at: io_submit_one+0xeb6/0x1cf0 fs/aio.c:1908 the dependencies between SOFTIRQ-irq-safe lock and the holding lock: -> (&(&ctx->ctx_lock)->rlock){..-.} { IN-SOFTIRQ-W at: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:160 spin_lock_irq include/linux/spinlock.h:354 [inline] free_ioctx_users+0x2d/0x4a0 fs/aio.c:610 percpu_ref_put_many include/linux/percpu-refcount.h:285 [inline] percpu_ref_put include/linux/percpu-refcount.h:301 [inline] percpu_ref_call_confirm_rcu lib/percpu-refcount.c:123 [inline] percpu_ref_switch_to_atomic_rcu+0x3e7/0x520 lib/percpu-refcount.c:158 __rcu_reclaim kernel/rcu/rcu.h:240 [inline] rcu_do_batch kernel/rcu/tree.c:2486 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2799 [inline] rcu_core+0x928/0x1390 kernel/rcu/tree.c:2780 __do_softirq+0x266/0x95a kernel/softirq.c:292 run_ksoftirqd kernel/softirq.c:654 [inline] run_ksoftirqd+0x8e/0x110 kernel/softirq.c:646 smpboot_thread_fn+0x6ab/0xa10 kernel/smpboot.c:164 kthread+0x357/0x430 kernel/kthread.c:247 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 INITIAL USE at: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline] _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:160 spin_lock_irq include/linux/spinlock.h:354 [inline] __do_sys_io_cancel fs/aio.c:2052 [inline] __se_sys_io_cancel fs/aio.c:2035 [inline] __x64_sys_io_cancel+0xd5/0x5a0 fs/aio.c:2035 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe } ... key at: [] __key.52370+0x0/0x40 ... acquired at: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] aio_poll fs/aio.c:1772 [inline] __io_submit_one fs/aio.c:1875 [inline] io_submit_one+0xedf/0x1cf0 fs/aio.c:1908 __do_sys_io_submit fs/aio.c:1953 [inline] __se_sys_io_submit fs/aio.c:1923 [inline] __x64_sys_io_submit+0x1bd/0x580 fs/aio.c:1923 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock: -> (&fiq->waitq){+.+.} { HARDIRQ-ON-W at: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415 fuse_request_queue_background+0x2d1/0x580 fs/fuse/dev.c:676 fuse_request_send_background+0x58/0x120 fs/fuse/dev.c:687 fuse_send_init fs/fuse/inode.c:989 [inline] fuse_fill_super+0x13bb/0x1730 fs/fuse/inode.c:1214 mount_nodev+0x68/0x110 fs/super.c:1392 fuse_mount+0x2d/0x40 fs/fuse/inode.c:1239 legacy_get_tree+0xf2/0x200 fs/fs_context.c:590 vfs_get_tree+0x123/0x450 fs/super.c:1481 do_new_mount fs/namespace.c:2610 [inline] do_mount+0x1436/0x2c40 fs/namespace.c:2932 ksys_mount+0xdb/0x150 fs/namespace.c:3148 __do_sys_mount fs/namespace.c:3162 [inline] __se_sys_mount fs/namespace.c:3159 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3159 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe SOFTIRQ-ON-W at: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415 fuse_request_queue_background+0x2d1/0x580 fs/fuse/dev.c:676 fuse_request_send_background+0x58/0x120 fs/fuse/dev.c:687 fuse_send_init fs/fuse/inode.c:989 [inline] fuse_fill_super+0x13bb/0x1730 fs/fuse/inode.c:1214 mount_nodev+0x68/0x110 fs/super.c:1392 fuse_mount+0x2d/0x40 fs/fuse/inode.c:1239 legacy_get_tree+0xf2/0x200 fs/fs_context.c:590 vfs_get_tree+0x123/0x450 fs/super.c:1481 do_new_mount fs/namespace.c:2610 [inline] do_mount+0x1436/0x2c40 fs/namespace.c:2932 ksys_mount+0xdb/0x150 fs/namespace.c:3148 __do_sys_mount fs/namespace.c:3162 [inline] __se_sys_mount fs/namespace.c:3159 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3159 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe INITIAL USE at: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415 fuse_request_queue_background+0x2d1/0x580 fs/fuse/dev.c:676 fuse_request_send_background+0x58/0x120 fs/fuse/dev.c:687 fuse_send_init fs/fuse/inode.c:989 [inline] fuse_fill_super+0x13bb/0x1730 fs/fuse/inode.c:1214 mount_nodev+0x68/0x110 fs/super.c:1392 fuse_mount+0x2d/0x40 fs/fuse/inode.c:1239 legacy_get_tree+0xf2/0x200 fs/fs_context.c:590 vfs_get_tree+0x123/0x450 fs/super.c:1481 do_new_mount fs/namespace.c:2610 [inline] do_mount+0x1436/0x2c40 fs/namespace.c:2932 ksys_mount+0xdb/0x150 fs/namespace.c:3148 __do_sys_mount fs/namespace.c:3162 [inline] __se_sys_mount fs/namespace.c:3159 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3159 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe } ... key at: [] __key.43450+0x0/0x40 ... acquired at: lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] aio_poll fs/aio.c:1772 [inline] __io_submit_one fs/aio.c:1875 [inline] io_submit_one+0xedf/0x1cf0 fs/aio.c:1908 __do_sys_io_submit fs/aio.c:1953 [inline] __se_sys_io_submit fs/aio.c:1923 [inline] __x64_sys_io_submit+0x1bd/0x580 fs/aio.c:1923 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe stack backtrace: CPU: 0 PID: 13779 Comm: syz-executor2 Not tainted 5.0.0-rc4-next-20190131 #23 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_bad_irq_dependency kernel/locking/lockdep.c:1573 [inline] check_usage.cold+0x60f/0x940 kernel/locking/lockdep.c:1605 check_irq_usage kernel/locking/lockdep.c:1650 [inline] check_prev_add_irq kernel/locking/lockdep_states.h:8 [inline] check_prev_add kernel/locking/lockdep.c:1860 [inline] check_prevs_add kernel/locking/lockdep.c:1968 [inline] validate_chain kernel/locking/lockdep.c:2339 [inline] __lock_acquire+0x1f12/0x4790 kernel/locking/lockdep.c:3320 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3826 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:144 spin_lock include/linux/spinlock.h:329 [inline] aio_poll fs/aio.c:1772 [inline] __io_submit_one fs/aio.c:1875 [inline] io_submit_one+0xedf/0x1cf0 fs/aio.c:1908 __do_sys_io_submit fs/aio.c:1953 [inline] __se_sys_io_submit fs/aio.c:1923 [inline] __x64_sys_io_submit+0x1bd/0x580 fs/aio.c:1923 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Reported-by: syzbot Cc: Christoph Hellwig Cc: Avi Kivity Cc: Miklos Szeredi Cc: Fixes: e8693bcfa0b4 ("aio: allow direct aio poll comletions for keyed wakeups") # v4.19 Signed-off-by: Miklos Szeredi [ bvanassche: added a comment ] Reluctantly-Acked-by: Christoph Hellwig Signed-off-by: Bart Van Assche Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

Merge tag 'for-linus-20181214' of git://git.kernel.dk/linux-block

2018-12-14T20:18:30Z

Pull block fixes from Jens Axboe: "Three small fixes for this week. contains: - spectre indexing fix for aio (Jeff) - fix for the previous zeroing bio fix, we don't need it for user mapped pages, and in fact it breaks some applications if we do (Keith) - allocation failure fix for null_blk with zoned (Shin'ichiro)" * tag 'for-linus-20181214' of git://git.kernel.dk/linux-block: block: Fix null_blk_zoned creation failure with small number of zones aio: fix spectre gadget in lookup_ioctx block/bio: Do not zero user pages

aio: fix spectre gadget in lookup_ioctx

2018-12-11T18:45:50Z

Matthew pointed out that the ioctx_table is susceptible to spectre v1, because the index can be controlled by an attacker. The below patch should mitigate the attack for all of the aio system calls. Cc: stable@vger.kernel.org Reported-by: Matthew Wilcox Reported-by: Dan Carpenter Signed-off-by: Jeff Moyer Signed-off-by: Jens Axboe

aio: fix failure to put the file pointer

2018-11-17T15:05:07Z

If the ioprio capability check fails, we return without putting the file pointer. Fixes: d9a08a9e616b ("fs: Add aio iopriority support") Signed-off-by: Jens Axboe Signed-off-by: Al Viro

y2038: globally rename compat_time to old_time32

2018-08-27T12:48:48Z

Christoph Hellwig suggested a slightly different path for handling backwards compatibility with the 32-bit time_t based system calls: Rather than simply reusing the compat_sys_* entry points on 32-bit architectures unchanged, we get rid of those entry points and the compat_time types by renaming them to something that makes more sense on 32-bit architectures (which don't have a compat mode otherwise), and then share the entry points under the new name with the 64-bit architectures that use them for implementing the compatibility. The following types and interfaces are renamed here, and moved from linux/compat_time.h to linux/time32.h: old new --- --- compat_time_t old_time32_t struct compat_timeval struct old_timeval32 struct compat_timespec struct old_timespec32 struct compat_itimerspec struct old_itimerspec32 ns_to_compat_timeval() ns_to_old_timeval32() get_compat_itimerspec64() get_old_itimerspec32() put_compat_itimerspec64() put_old_itimerspec32() compat_get_timespec64() get_old_timespec32() compat_put_timespec64() put_old_timespec32() As we already have aliases in place, this patch addresses only the instances that are relevant to the system call interface in particular, not those that occur in device drivers and other modules. Those will get handled separately, while providing the 64-bit version of the respective interfaces. I'm not renaming the timex, rusage and itimerval structures, as we are still debating what the new interface will look like, and whether we will need a replacement at all. This also doesn't change the names of the syscall entry points, which can be done more easily when we actually switch over the 32-bit architectures to use them, at that point we need to change COMPAT_SYSCALL_DEFINEx to SYSCALL_DEFINEx with a new name, e.g. with a _time32 suffix. Suggested-by: Christoph Hellwig Link: https://lore.kernel.org/lkml/20180705222110.GA5698@infradead.org/ Signed-off-by: Arnd Bergmann

Merge branch 'work.aio' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2018-08-14T03:56:23Z

Pull vfs aio updates from Al Viro: "Christoph's aio poll, saner this time around. This time it's pretty much local to fs/aio.c. Hopefully race-free..." * 'work.aio' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: aio: allow direct aio poll comletions for keyed wakeups aio: implement IOCB_CMD_POLL aio: add a iocb refcount timerfd: add support for keyed wakeups

Merge branch 'work.open3' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2018-08-14T02:58:36Z

Pull vfs open-related updates from Al Viro: - "do we need fput() or put_filp()" rules are gone - it's always fput() now. We keep track of that state where it belongs - in ->f_mode. - int *opened mess killed - in finish_open(), in ->atomic_open() instances and in fs/namei.c code around do_last()/lookup_open()/atomic_open(). - alloc_file() wrappers with saner calling conventions are introduced (alloc_file_clone() and alloc_file_pseudo()); callers converted, with much simplification. - while we are at it, saner calling conventions for path_init() and link_path_walk(), simplifying things inside fs/namei.c (both on open-related paths and elsewhere). * 'work.open3' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (40 commits) few more cleanups of link_path_walk() callers allow link_path_walk() to take ERR_PTR() make path_init() unconditionally paired with terminate_walk() document alloc_file() changes make alloc_file() static do_shmat(): grab shp->shm_file earlier, switch to alloc_file_clone() new helper: alloc_file_clone() create_pipe_files(): switch the first allocation to alloc_file_pseudo() anon_inode_getfile(): switch to alloc_file_pseudo() hugetlb_file_setup(): switch to alloc_file_pseudo() ocxlflash_getfile(): switch to alloc_file_pseudo() cxl_getfile(): switch to alloc_file_pseudo() ... and switch shmem_file_setup() to alloc_file_pseudo() __shmem_file_setup(): reorder allocations new wrapper: alloc_file_pseudo() kill FILE_{CREATED,OPENED} switch atomic_open() and lookup_open() to returning 0 in all success cases document ->atomic_open() changes ->atomic_open(): return 0 in all success cases get rid of 'opened' in path_openat() and the helpers downstream ...

aio: allow direct aio poll comletions for keyed wakeups

2018-08-06T08:24:39Z

If we get a keyed wakeup for a aio poll waitqueue and wake can acquire the ctx_lock without spinning we can just complete the iocb straight from the wakeup callback to avoid a context switch. Signed-off-by: Christoph Hellwig Tested-by: Avi Kivity

aio: implement IOCB_CMD_POLL

2018-08-06T08:24:33Z

Simple one-shot poll through the io_submit() interface. To poll for a file descriptor the application should submit an iocb of type IOCB_CMD_POLL. It will poll the fd for the events specified in the the first 32 bits of the aio_buf field of the iocb. Unlike poll or epoll without EPOLLONESHOT this interface always works in one shot mode, that is once the iocb is completed, it will have to be resubmitted. Signed-off-by: Christoph Hellwig Tested-by: Avi Kivity

aio: add a iocb refcount

2018-08-06T08:24:28Z

This is needed to prevent races caused by the way the ->poll API works. To avoid introducing overhead for other users of the iocbs we initialize it to zero and only do refcount operations if it is non-zero in the completion path. Signed-off-by: Christoph Hellwig Tested-by: Avi Kivity