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/9p/fid.c | 316 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 316 insertions(+) create mode 100644 fs/9p/fid.c (limited to 'fs/9p/fid.c') diff --git a/fs/9p/fid.c b/fs/9p/fid.c new file mode 100644 index 000000000..76242d450 --- /dev/null +++ b/fs/9p/fid.c @@ -0,0 +1,316 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * V9FS FID Management + * + * Copyright (C) 2007 by Latchesar Ionkov + * Copyright (C) 2005, 2006 by Eric Van Hensbergen + */ + +#include +#include +#include +#include +#include +#include +#include + +#include "v9fs.h" +#include "v9fs_vfs.h" +#include "fid.h" + +static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid) +{ + struct v9fs_dentry *v9fs_dentry = to_v9fs_dentry(dentry); + + hlist_add_head(&fid->dlist, &v9fs_dentry->head); +} + + +/** + * v9fs_fid_add - add a fid to a dentry + * @dentry: dentry that the fid is being added to + * @pfid: fid to add, NULLed out + * + */ +void v9fs_fid_add(struct dentry *dentry, struct p9_fid **pfid) +{ + struct p9_fid *fid = *pfid; + + spin_lock(&dentry->d_lock); + __add_fid(dentry, fid); + spin_unlock(&dentry->d_lock); + + *pfid = NULL; +} + +static bool v9fs_is_writeable(int mode) +{ + if (mode & (P9_OWRITE|P9_ORDWR)) + return true; + else + return false; +} + +/** + * v9fs_fid_find_inode - search for an open fid off of the inode list + * @inode: return a fid pointing to a specific inode + * @want_writeable: only consider fids which are writeable + * @uid: return a fid belonging to the specified user + * @any: ignore uid as a selection criteria + * + */ +struct p9_fid *v9fs_fid_find_inode(struct inode *inode, bool want_writeable, + kuid_t uid, bool any) +{ + struct hlist_head *h; + struct p9_fid *fid, *ret = NULL; + + p9_debug(P9_DEBUG_VFS, " inode: %p\n", inode); + + spin_lock(&inode->i_lock); + h = (struct hlist_head *)&inode->i_private; + hlist_for_each_entry(fid, h, ilist) { + if (any || uid_eq(fid->uid, uid)) { + if (want_writeable && !v9fs_is_writeable(fid->mode)) { + p9_debug(P9_DEBUG_VFS, " mode: %x not writeable?\n", + fid->mode); + continue; + } + p9_fid_get(fid); + ret = fid; + break; + } + } + spin_unlock(&inode->i_lock); + return ret; +} + +/** + * v9fs_open_fid_add - add an open fid to an inode + * @inode: inode that the fid is being added to + * @pfid: fid to add, NULLed out + * + */ + +void v9fs_open_fid_add(struct inode *inode, struct p9_fid **pfid) +{ + struct p9_fid *fid = *pfid; + + spin_lock(&inode->i_lock); + hlist_add_head(&fid->ilist, (struct hlist_head *)&inode->i_private); + spin_unlock(&inode->i_lock); + + *pfid = NULL; +} + + +/** + * v9fs_fid_find - retrieve a fid that belongs to the specified uid + * @dentry: dentry to look for fid in + * @uid: return fid that belongs to the specified user + * @any: if non-zero, return any fid associated with the dentry + * + */ + +static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any) +{ + struct v9fs_dentry *v9fs_dentry = to_v9fs_dentry(dentry); + struct p9_fid *fid, *ret; + + p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n", + dentry, dentry, from_kuid(&init_user_ns, uid), + any); + ret = NULL; + /* we'll recheck under lock if there's anything to look in */ + if (!hlist_empty(&v9fs_dentry->head)) { + spin_lock(&dentry->d_lock); + hlist_for_each_entry(fid, &v9fs_dentry->head, dlist) { + if (any || uid_eq(fid->uid, uid)) { + ret = fid; + p9_fid_get(ret); + break; + } + } + spin_unlock(&dentry->d_lock); + } + if (!ret && dentry->d_inode) + ret = v9fs_fid_find_inode(dentry->d_inode, false, uid, any); + + return ret; +} + +/* + * We need to hold v9ses->rename_sem as long as we hold references + * to returned path array. Array element contain pointers to + * dentry names. + */ +static int build_path_from_dentry(struct v9fs_session_info *v9ses, + struct dentry *dentry, const unsigned char ***names) +{ + int n = 0, i; + const unsigned char **wnames; + struct dentry *ds; + + for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) + n++; + + wnames = kmalloc_array(n, sizeof(char *), GFP_KERNEL); + if (!wnames) + goto err_out; + + for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent) + wnames[i] = ds->d_name.name; + + *names = wnames; + return n; +err_out: + return -ENOMEM; +} + +static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry, + kuid_t uid, int any) +{ + struct dentry *ds; + const unsigned char **wnames, *uname; + int i, n, l, access; + struct v9fs_session_info *v9ses; + struct p9_fid *fid, *root_fid, *old_fid; + + v9ses = v9fs_dentry2v9ses(dentry); + access = v9ses->flags & V9FS_ACCESS_MASK; + fid = v9fs_fid_find(dentry, uid, any); + if (fid) + return fid; + /* + * we don't have a matching fid. To do a TWALK we need + * parent fid. We need to prevent rename when we want to + * look at the parent. + */ + down_read(&v9ses->rename_sem); + ds = dentry->d_parent; + fid = v9fs_fid_find(ds, uid, any); + if (fid) { + /* Found the parent fid do a lookup with that */ + old_fid = fid; + + fid = p9_client_walk(old_fid, 1, &dentry->d_name.name, 1); + p9_fid_put(old_fid); + goto fid_out; + } + up_read(&v9ses->rename_sem); + + /* start from the root and try to do a lookup */ + root_fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any); + if (!root_fid) { + /* the user is not attached to the fs yet */ + if (access == V9FS_ACCESS_SINGLE) + return ERR_PTR(-EPERM); + + if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) + uname = NULL; + else + uname = v9ses->uname; + + fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, + v9ses->aname); + if (IS_ERR(fid)) + return fid; + + root_fid = p9_fid_get(fid); + v9fs_fid_add(dentry->d_sb->s_root, &fid); + } + /* If we are root ourself just return that */ + if (dentry->d_sb->s_root == dentry) + return root_fid; + + /* + * Do a multipath walk with attached root. + * When walking parent we need to make sure we + * don't have a parallel rename happening + */ + down_read(&v9ses->rename_sem); + n = build_path_from_dentry(v9ses, dentry, &wnames); + if (n < 0) { + fid = ERR_PTR(n); + goto err_out; + } + fid = root_fid; + old_fid = root_fid; + i = 0; + while (i < n) { + l = min(n - i, P9_MAXWELEM); + /* + * We need to hold rename lock when doing a multipath + * walk to ensure none of the path components change + */ + fid = p9_client_walk(old_fid, l, &wnames[i], + old_fid == root_fid /* clone */); + /* non-cloning walk will return the same fid */ + if (fid != old_fid) { + p9_fid_put(old_fid); + old_fid = fid; + } + if (IS_ERR(fid)) { + kfree(wnames); + goto err_out; + } + i += l; + } + kfree(wnames); +fid_out: + if (!IS_ERR(fid)) { + spin_lock(&dentry->d_lock); + if (d_unhashed(dentry)) { + spin_unlock(&dentry->d_lock); + p9_fid_put(fid); + fid = ERR_PTR(-ENOENT); + } else { + __add_fid(dentry, fid); + p9_fid_get(fid); + spin_unlock(&dentry->d_lock); + } + } +err_out: + up_read(&v9ses->rename_sem); + return fid; +} + +/** + * v9fs_fid_lookup - lookup for a fid, try to walk if not found + * @dentry: dentry to look for fid in + * + * Look for a fid in the specified dentry for the current user. + * If no fid is found, try to create one walking from a fid from the parent + * dentry (if it has one), or the root dentry. If the user haven't accessed + * the fs yet, attach now and walk from the root. + */ + +struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) +{ + kuid_t uid; + int any, access; + struct v9fs_session_info *v9ses; + + v9ses = v9fs_dentry2v9ses(dentry); + access = v9ses->flags & V9FS_ACCESS_MASK; + switch (access) { + case V9FS_ACCESS_SINGLE: + case V9FS_ACCESS_USER: + case V9FS_ACCESS_CLIENT: + uid = current_fsuid(); + any = 0; + break; + + case V9FS_ACCESS_ANY: + uid = v9ses->uid; + any = 1; + break; + + default: + uid = INVALID_UID; + any = 0; + break; + } + return v9fs_fid_lookup_with_uid(dentry, uid, any); +} + -- cgit v1.3.1