From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- fs/autofs/waitq.c | 513 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 513 insertions(+) create mode 100644 fs/autofs/waitq.c (limited to 'fs/autofs/waitq.c') diff --git a/fs/autofs/waitq.c b/fs/autofs/waitq.c new file mode 100644 index 000000000..d46241342 --- /dev/null +++ b/fs/autofs/waitq.c @@ -0,0 +1,513 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved + * Copyright 2001-2006 Ian Kent + */ + +#include +#include "autofs_i.h" + +/* We make this a static variable rather than a part of the superblock; it + * is better if we don't reassign numbers easily even across filesystems + */ +static autofs_wqt_t autofs_next_wait_queue = 1; + +void autofs_catatonic_mode(struct autofs_sb_info *sbi) +{ + struct autofs_wait_queue *wq, *nwq; + + mutex_lock(&sbi->wq_mutex); + if (sbi->flags & AUTOFS_SBI_CATATONIC) { + mutex_unlock(&sbi->wq_mutex); + return; + } + + pr_debug("entering catatonic mode\n"); + + sbi->flags |= AUTOFS_SBI_CATATONIC; + wq = sbi->queues; + sbi->queues = NULL; /* Erase all wait queues */ + while (wq) { + nwq = wq->next; + wq->status = -ENOENT; /* Magic is gone - report failure */ + kfree(wq->name.name - wq->offset); + wq->name.name = NULL; + wake_up(&wq->queue); + if (!--wq->wait_ctr) + kfree(wq); + wq = nwq; + } + fput(sbi->pipe); /* Close the pipe */ + sbi->pipe = NULL; + sbi->pipefd = -1; + mutex_unlock(&sbi->wq_mutex); +} + +static int autofs_write(struct autofs_sb_info *sbi, + struct file *file, const void *addr, int bytes) +{ + unsigned long sigpipe, flags; + const char *data = (const char *)addr; + ssize_t wr = 0; + + sigpipe = sigismember(¤t->pending.signal, SIGPIPE); + + mutex_lock(&sbi->pipe_mutex); + while (bytes) { + wr = __kernel_write(file, data, bytes, NULL); + if (wr <= 0) + break; + data += wr; + bytes -= wr; + } + mutex_unlock(&sbi->pipe_mutex); + + /* Keep the currently executing process from receiving a + * SIGPIPE unless it was already supposed to get one + */ + if (wr == -EPIPE && !sigpipe) { + spin_lock_irqsave(¤t->sighand->siglock, flags); + sigdelset(¤t->pending.signal, SIGPIPE); + recalc_sigpending(); + spin_unlock_irqrestore(¤t->sighand->siglock, flags); + } + + /* if 'wr' returned 0 (impossible) we assume -EIO (safe) */ + return bytes == 0 ? 0 : wr < 0 ? wr : -EIO; +} + +static void autofs_notify_daemon(struct autofs_sb_info *sbi, + struct autofs_wait_queue *wq, + int type) +{ + union { + struct autofs_packet_hdr hdr; + union autofs_packet_union v4_pkt; + union autofs_v5_packet_union v5_pkt; + } pkt; + struct file *pipe = NULL; + size_t pktsz; + int ret; + + pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n", + (unsigned long) wq->wait_queue_token, + wq->name.len, wq->name.name, type); + + memset(&pkt, 0, sizeof(pkt)); /* For security reasons */ + + pkt.hdr.proto_version = sbi->version; + pkt.hdr.type = type; + + switch (type) { + /* Kernel protocol v4 missing and expire packets */ + case autofs_ptype_missing: + { + struct autofs_packet_missing *mp = &pkt.v4_pkt.missing; + + pktsz = sizeof(*mp); + + mp->wait_queue_token = wq->wait_queue_token; + mp->len = wq->name.len; + memcpy(mp->name, wq->name.name, wq->name.len); + mp->name[wq->name.len] = '\0'; + break; + } + case autofs_ptype_expire_multi: + { + struct autofs_packet_expire_multi *ep = + &pkt.v4_pkt.expire_multi; + + pktsz = sizeof(*ep); + + ep->wait_queue_token = wq->wait_queue_token; + ep->len = wq->name.len; + memcpy(ep->name, wq->name.name, wq->name.len); + ep->name[wq->name.len] = '\0'; + break; + } + /* + * Kernel protocol v5 packet for handling indirect and direct + * mount missing and expire requests + */ + case autofs_ptype_missing_indirect: + case autofs_ptype_expire_indirect: + case autofs_ptype_missing_direct: + case autofs_ptype_expire_direct: + { + struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet; + struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns; + + pktsz = sizeof(*packet); + + packet->wait_queue_token = wq->wait_queue_token; + packet->len = wq->name.len; + memcpy(packet->name, wq->name.name, wq->name.len); + packet->name[wq->name.len] = '\0'; + packet->dev = wq->dev; + packet->ino = wq->ino; + packet->uid = from_kuid_munged(user_ns, wq->uid); + packet->gid = from_kgid_munged(user_ns, wq->gid); + packet->pid = wq->pid; + packet->tgid = wq->tgid; + break; + } + default: + pr_warn("bad type %d!\n", type); + mutex_unlock(&sbi->wq_mutex); + return; + } + + pipe = get_file(sbi->pipe); + + mutex_unlock(&sbi->wq_mutex); + + switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) { + case 0: + break; + case -ENOMEM: + case -ERESTARTSYS: + /* Just fail this one */ + autofs_wait_release(sbi, wq->wait_queue_token, ret); + break; + default: + autofs_catatonic_mode(sbi); + break; + } + fput(pipe); +} + +static struct autofs_wait_queue * +autofs_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr) +{ + struct autofs_wait_queue *wq; + + for (wq = sbi->queues; wq; wq = wq->next) { + if (wq->name.hash == qstr->hash && + wq->name.len == qstr->len && + wq->name.name && + !memcmp(wq->name.name, qstr->name, qstr->len)) + break; + } + return wq; +} + +/* + * Check if we have a valid request. + * Returns + * 1 if the request should continue. + * In this case we can return an autofs_wait_queue entry if one is + * found or NULL to idicate a new wait needs to be created. + * 0 or a negative errno if the request shouldn't continue. + */ +static int validate_request(struct autofs_wait_queue **wait, + struct autofs_sb_info *sbi, + const struct qstr *qstr, + const struct path *path, enum autofs_notify notify) +{ + struct dentry *dentry = path->dentry; + struct autofs_wait_queue *wq; + struct autofs_info *ino; + + if (sbi->flags & AUTOFS_SBI_CATATONIC) + return -ENOENT; + + /* Wait in progress, continue; */ + wq = autofs_find_wait(sbi, qstr); + if (wq) { + *wait = wq; + return 1; + } + + *wait = NULL; + + /* If we don't yet have any info this is a new request */ + ino = autofs_dentry_ino(dentry); + if (!ino) + return 1; + + /* + * If we've been asked to wait on an existing expire (NFY_NONE) + * but there is no wait in the queue ... + */ + if (notify == NFY_NONE) { + /* + * Either we've betean the pending expire to post it's + * wait or it finished while we waited on the mutex. + * So we need to wait till either, the wait appears + * or the expire finishes. + */ + + while (ino->flags & AUTOFS_INF_EXPIRING) { + mutex_unlock(&sbi->wq_mutex); + schedule_timeout_interruptible(HZ/10); + if (mutex_lock_interruptible(&sbi->wq_mutex)) + return -EINTR; + + if (sbi->flags & AUTOFS_SBI_CATATONIC) + return -ENOENT; + + wq = autofs_find_wait(sbi, qstr); + if (wq) { + *wait = wq; + return 1; + } + } + + /* + * Not ideal but the status has already gone. Of the two + * cases where we wait on NFY_NONE neither depend on the + * return status of the wait. + */ + return 0; + } + + /* + * If we've been asked to trigger a mount and the request + * completed while we waited on the mutex ... + */ + if (notify == NFY_MOUNT) { + struct dentry *new = NULL; + struct path this; + int valid = 1; + + /* + * If the dentry was successfully mounted while we slept + * on the wait queue mutex we can return success. If it + * isn't mounted (doesn't have submounts for the case of + * a multi-mount with no mount at it's base) we can + * continue on and create a new request. + */ + if (!IS_ROOT(dentry)) { + if (d_unhashed(dentry) && + d_really_is_positive(dentry)) { + struct dentry *parent = dentry->d_parent; + + new = d_lookup(parent, &dentry->d_name); + if (new) + dentry = new; + } + } + this.mnt = path->mnt; + this.dentry = dentry; + if (path_has_submounts(&this)) + valid = 0; + + if (new) + dput(new); + return valid; + } + + return 1; +} + +int autofs_wait(struct autofs_sb_info *sbi, + const struct path *path, enum autofs_notify notify) +{ + struct dentry *dentry = path->dentry; + struct autofs_wait_queue *wq; + struct qstr qstr; + char *name; + int status, ret, type; + unsigned int offset = 0; + pid_t pid; + pid_t tgid; + + /* In catatonic mode, we don't wait for nobody */ + if (sbi->flags & AUTOFS_SBI_CATATONIC) + return -ENOENT; + + /* + * Try translating pids to the namespace of the daemon. + * + * Zero means failure: we are in an unrelated pid namespace. + */ + pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp)); + tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp)); + if (pid == 0 || tgid == 0) + return -ENOENT; + + if (d_really_is_negative(dentry)) { + /* + * A wait for a negative dentry is invalid for certain + * cases. A direct or offset mount "always" has its mount + * point directory created and so the request dentry must + * be positive or the map key doesn't exist. The situation + * is very similar for indirect mounts except only dentrys + * in the root of the autofs file system may be negative. + */ + if (autofs_type_trigger(sbi->type)) + return -ENOENT; + else if (!IS_ROOT(dentry->d_parent)) + return -ENOENT; + } + + name = kmalloc(NAME_MAX + 1, GFP_KERNEL); + if (!name) + return -ENOMEM; + + /* If this is a direct mount request create a dummy name */ + if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type)) { + qstr.name = name; + qstr.len = sprintf(name, "%p", dentry); + } else { + char *p = dentry_path_raw(dentry, name, NAME_MAX); + if (IS_ERR(p)) { + kfree(name); + return -ENOENT; + } + qstr.name = ++p; // skip the leading slash + qstr.len = strlen(p); + offset = p - name; + } + qstr.hash = full_name_hash(dentry, qstr.name, qstr.len); + + if (mutex_lock_interruptible(&sbi->wq_mutex)) { + kfree(name); + return -EINTR; + } + + ret = validate_request(&wq, sbi, &qstr, path, notify); + if (ret <= 0) { + if (ret != -EINTR) + mutex_unlock(&sbi->wq_mutex); + kfree(name); + return ret; + } + + if (!wq) { + /* Create a new wait queue */ + wq = kmalloc_obj(struct autofs_wait_queue); + if (!wq) { + kfree(name); + mutex_unlock(&sbi->wq_mutex); + return -ENOMEM; + } + + wq->wait_queue_token = autofs_next_wait_queue; + if (++autofs_next_wait_queue == 0) + autofs_next_wait_queue = 1; + wq->next = sbi->queues; + sbi->queues = wq; + init_waitqueue_head(&wq->queue); + memcpy(&wq->name, &qstr, sizeof(struct qstr)); + wq->offset = offset; + wq->dev = autofs_get_dev(sbi); + wq->ino = autofs_get_ino(sbi); + wq->uid = current_uid(); + wq->gid = current_gid(); + wq->pid = pid; + wq->tgid = tgid; + wq->status = -EINTR; /* Status return if interrupted */ + wq->wait_ctr = 2; + + if (sbi->version < 5) { + if (notify == NFY_MOUNT) + type = autofs_ptype_missing; + else + type = autofs_ptype_expire_multi; + } else { + if (notify == NFY_MOUNT) + type = autofs_type_trigger(sbi->type) ? + autofs_ptype_missing_direct : + autofs_ptype_missing_indirect; + else + type = autofs_type_trigger(sbi->type) ? + autofs_ptype_expire_direct : + autofs_ptype_expire_indirect; + } + + pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n", + (unsigned long) wq->wait_queue_token, wq->name.len, + wq->name.name, notify); + + /* + * autofs_notify_daemon() may block; it will unlock ->wq_mutex + */ + autofs_notify_daemon(sbi, wq, type); + } else { + wq->wait_ctr++; + pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n", + (unsigned long) wq->wait_queue_token, wq->name.len, + wq->name.name, notify); + mutex_unlock(&sbi->wq_mutex); + kfree(name); + } + + /* + * wq->name.name is NULL iff the lock is already released + * or the mount has been made catatonic. + */ + wait_event_killable(wq->queue, wq->name.name == NULL); + status = wq->status; + + /* + * For direct and offset mounts we need to track the requester's + * uid and gid in the dentry info struct. This is so it can be + * supplied, on request, by the misc device ioctl interface. + * This is needed during daemon resatart when reconnecting + * to existing, active, autofs mounts. The uid and gid (and + * related string values) may be used for macro substitution + * in autofs mount maps. + */ + if (!status) { + struct autofs_info *ino; + struct dentry *de = NULL; + + /* direct mount or browsable map */ + ino = autofs_dentry_ino(dentry); + if (!ino) { + /* If not lookup actual dentry used */ + de = d_lookup(dentry->d_parent, &dentry->d_name); + if (de) + ino = autofs_dentry_ino(de); + } + + /* Set mount requester */ + if (ino) { + spin_lock(&sbi->fs_lock); + ino->uid = wq->uid; + ino->gid = wq->gid; + spin_unlock(&sbi->fs_lock); + } + + if (de) + dput(de); + } + + /* Are we the last process to need status? */ + mutex_lock(&sbi->wq_mutex); + if (!--wq->wait_ctr) + kfree(wq); + mutex_unlock(&sbi->wq_mutex); + + return status; +} + + +int autofs_wait_release(struct autofs_sb_info *sbi, + autofs_wqt_t wait_queue_token, int status) +{ + struct autofs_wait_queue *wq, **wql; + + mutex_lock(&sbi->wq_mutex); + for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) { + if (wq->wait_queue_token == wait_queue_token) + break; + } + + if (!wq) { + mutex_unlock(&sbi->wq_mutex); + return -EINVAL; + } + + *wql = wq->next; /* Unlink from chain */ + kfree(wq->name.name - wq->offset); + wq->name.name = NULL; /* Do not wait on this queue */ + wq->status = status; + wake_up(&wq->queue); + if (!--wq->wait_ctr) + kfree(wq); + mutex_unlock(&sbi->wq_mutex); + + return 0; +} -- cgit v1.3.1