Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 573 insertions, 0 deletions

diff --git a/fs/readdir.c b/fs/readdir.c
new file mode 100644
index 000000000..76bb1ae3a
--- /dev/null
+++ b/fs/readdir.c
@@ -0,0 +1,573 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/readdir.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ */
+
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/time.h>
+#include <linux/mm.h>
+#include <linux/errno.h>
+#include <linux/stat.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/fsnotify.h>
+#include <linux/dirent.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/unistd.h>
+#include <linux/compat.h>
+#include <linux/uaccess.h>
+
+#define dirent_size(dirent, len) offsetof(typeof(*(dirent)), d_name[len])
+
+/*
+ * Some filesystems were never converted to '->iterate_shared()'
+ * and their directory iterators want the inode lock held for
+ * writing. This wrapper allows for converting from the shared
+ * semantics to the exclusive inode use.
+ */
+int wrap_directory_iterator(struct file *file,
+			    struct dir_context *ctx,
+			    int (*iter)(struct file *, struct dir_context *))
+{
+	struct inode *inode = file_inode(file);
+	int ret;
+
+	/*
+	 * We'd love to have an 'inode_upgrade_trylock()' operation,
+	 * see the comment in mmap_upgrade_trylock() in mm/memory.c.
+	 *
+	 * But considering this is for "filesystems that never got
+	 * converted", it really doesn't matter.
+	 *
+	 * Also note that since we have to return with the lock held
+	 * for reading, we can't use the "killable()" locking here,
+	 * since we do need to get the lock even if we're dying.
+	 *
+	 * We could do the write part killably and then get the read
+	 * lock unconditionally if it mattered, but see above on why
+	 * this does the very simplistic conversion.
+	 */
+	up_read(&inode->i_rwsem);
+	down_write(&inode->i_rwsem);
+
+	/*
+	 * Since we dropped the inode lock, we should do the
+	 * DEADDIR test again. See 'iterate_dir()' below.
+	 *
+	 * Note that we don't need to re-do the f_pos games,
+	 * since the file must be locked wrt f_pos anyway.
+	 */
+	ret = -ENOENT;
+	if (!IS_DEADDIR(inode))
+		ret = iter(file, ctx);
+
+	downgrade_write(&inode->i_rwsem);
+	return ret;
+}
+EXPORT_SYMBOL(wrap_directory_iterator);
+
+/*
+ * Note the "unsafe_put_user()" semantics: we goto a
+ * label for errors.
+ */
+#define unsafe_copy_dirent_name(_dst, _src, _len, label) do {	\
+	char __user *dst = (_dst);				\
+	const char *src = (_src);				\
+	size_t len = (_len);					\
+	unsafe_put_user(0, dst+len, label);			\
+	unsafe_copy_to_user(dst, src, len, label);		\
+} while (0)
+
+
+int iterate_dir(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	int res = -ENOTDIR;
+
+	if (!file->f_op->iterate_shared)
+		goto out;
+
+	res = security_file_permission(file, MAY_READ);
+	if (res)
+		goto out;
+
+	res = fsnotify_file_perm(file, MAY_READ);
+	if (res)
+		goto out;
+
+	res = down_read_killable(&inode->i_rwsem);
+	if (res)
+		goto out;
+
+	res = -ENOENT;
+	if (!IS_DEADDIR(inode)) {
+		ctx->pos = file->f_pos;
+		res = file->f_op->iterate_shared(file, ctx);
+		file->f_pos = ctx->pos;
+		fsnotify_access(file);
+		file_accessed(file);
+	}
+	inode_unlock_shared(inode);
+out:
+	return res;
+}
+EXPORT_SYMBOL(iterate_dir);
+
+/*
+ * POSIX says that a dirent name cannot contain NULL or a '/'.
+ *
+ * It's not 100% clear what we should really do in this case.
+ * The filesystem is clearly corrupted, but returning a hard
+ * error means that you now don't see any of the other names
+ * either, so that isn't a perfect alternative.
+ *
+ * And if you return an error, what error do you use? Several
+ * filesystems seem to have decided on EUCLEAN being the error
+ * code for EFSCORRUPTED, and that may be the error to use. Or
+ * just EIO, which is perhaps more obvious to users.
+ *
+ * In order to see the other file names in the directory, the
+ * caller might want to make this a "soft" error: skip the
+ * entry, and return the error at the end instead.
+ *
+ * Note that this should likely do a "memchr(name, 0, len)"
+ * check too, since that would be filesystem corruption as
+ * well. However, that case can't actually confuse user space,
+ * which has to do a strlen() on the name anyway to find the
+ * filename length, and the above "soft error" worry means
+ * that it's probably better left alone until we have that
+ * issue clarified.
+ *
+ * Note the PATH_MAX check - it's arbitrary but the real
+ * kernel limit on a possible path component, not NAME_MAX,
+ * which is the technical standard limit.
+ */
+static int verify_dirent_name(const char *name, int len)
+{
+	if (len <= 0 || len >= PATH_MAX)
+		return -EIO;
+	if (memchr(name, '/', len))
+		return -EIO;
+	return 0;
+}
+
+/*
+ * Traditional linux readdir() handling..
+ *
+ * "count=1" is a special case, meaning that the buffer is one
+ * dirent-structure in size and that the code can't handle more
+ * anyway. Thus the special "fillonedir()" function for that
+ * case (the low-level handlers don't need to care about this).
+ */
+
+#ifdef __ARCH_WANT_OLD_READDIR
+
+struct old_linux_dirent {
+	unsigned long	d_ino;
+	unsigned long	d_offset;
+	unsigned short	d_namlen;
+	char		d_name[];
+};
+
+struct readdir_callback {
+	struct dir_context ctx;
+	struct old_linux_dirent __user * dirent;
+	int result;
+};
+
+static bool fillonedir(struct dir_context *ctx, const char *name, int namlen,
+		      loff_t offset, u64 ino, unsigned int d_type)
+{
+	struct readdir_callback *buf =
+		container_of(ctx, struct readdir_callback, ctx);
+	struct old_linux_dirent __user * dirent;
+	unsigned long d_ino;
+
+	if (buf->result)
+		return false;
+	buf->result = verify_dirent_name(name, namlen);
+	if (buf->result)
+		return false;
+	d_ino = ino;
+	if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
+		buf->result = -EOVERFLOW;
+		return false;
+	}
+	buf->result++;
+	dirent = buf->dirent;
+	scoped_user_write_access_size(dirent, dirent_size(dirent, namlen + 1), efault) {
+		unsafe_put_user(d_ino, &dirent->d_ino, efault);
+		unsafe_put_user(offset, &dirent->d_offset, efault);
+		unsafe_put_user(namlen, &dirent->d_namlen, efault);
+		unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault);
+	}
+	return true;
+efault:
+	buf->result = -EFAULT;
+	return false;
+}
+
+SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
+		struct old_linux_dirent __user *, dirent, unsigned int, count)
+{
+	int error;
+	CLASS(fd_pos, f)(fd);
+	struct readdir_callback buf = {
+		.ctx.actor = fillonedir,
+		.ctx.count = 1, /* Hint to fs: just one entry. */
+		.dirent = dirent
+	};
+
+	if (fd_empty(f))
+		return -EBADF;
+
+	error = iterate_dir(fd_file(f), &buf.ctx);
+	if (buf.result)
+		error = buf.result;
+
+	return error;
+}
+
+#endif /* __ARCH_WANT_OLD_READDIR */
+
+/*
+ * New, all-improved, singing, dancing, iBCS2-compliant getdents()
+ * interface. 
+ */
+struct linux_dirent {
+	unsigned long	d_ino;
+	unsigned long	d_off;
+	unsigned short	d_reclen;
+	char		d_name[];
+};
+
+struct getdents_callback {
+	struct dir_context ctx;
+	struct linux_dirent __user * current_dir;
+	int prev_reclen;
+	int error;
+};
+
+static bool filldir(struct dir_context *ctx, const char *name, int namlen,
+		   loff_t offset, u64 ino, unsigned int d_type)
+{
+	struct linux_dirent __user *dirent, *prev;
+	struct getdents_callback *buf =
+		container_of(ctx, struct getdents_callback, ctx);
+	unsigned long d_ino;
+	int reclen = ALIGN(dirent_size(dirent, namlen + 2), sizeof(long));
+	int prev_reclen;
+	unsigned int flags = d_type;
+
+	BUILD_BUG_ON(FILLDIR_FLAG_NOINTR & S_DT_MASK);
+	d_type &= S_DT_MASK;
+
+	buf->error = verify_dirent_name(name, namlen);
+	if (unlikely(buf->error))
+		return false;
+	buf->error = -EINVAL;	/* only used if we fail.. */
+	if (reclen > ctx->count)
+		return false;
+	d_ino = ino;
+	if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
+		buf->error = -EOVERFLOW;
+		return false;
+	}
+	prev_reclen = buf->prev_reclen;
+	if (!(flags & FILLDIR_FLAG_NOINTR) && prev_reclen && signal_pending(current))
+		return false;
+	dirent = buf->current_dir;
+	prev = (void __user *) dirent - prev_reclen;
+	scoped_user_write_access_size(prev, reclen + prev_reclen, efault) {
+		/* This might be 'dirent->d_off', but if so it will get overwritten */
+		unsafe_put_user(offset, &prev->d_off, efault);
+		unsafe_put_user(d_ino, &dirent->d_ino, efault);
+		unsafe_put_user(reclen, &dirent->d_reclen, efault);
+		unsafe_put_user(d_type, (char __user *)dirent + reclen - 1, efault);
+		unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault);
+	}
+
+	buf->current_dir = (void __user *)dirent + reclen;
+	buf->prev_reclen = reclen;
+	ctx->count -= reclen;
+	return true;
+efault:
+	buf->error = -EFAULT;
+	return false;
+}
+
+SYSCALL_DEFINE3(getdents, unsigned int, fd,
+		struct linux_dirent __user *, dirent, unsigned int, count)
+{
+	CLASS(fd_pos, f)(fd);
+	struct getdents_callback buf = {
+		.ctx.actor = filldir,
+		.ctx.count = count,
+		.ctx.dt_flags_mask = FILLDIR_FLAG_NOINTR,
+		.current_dir = dirent
+	};
+	int error;
+
+	if (fd_empty(f))
+		return -EBADF;
+
+	error = iterate_dir(fd_file(f), &buf.ctx);
+	if (error >= 0)
+		error = buf.error;
+	if (buf.prev_reclen) {
+		struct linux_dirent __user * lastdirent;
+		lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
+
+		if (put_user(buf.ctx.pos, &lastdirent->d_off))
+			error = -EFAULT;
+		else
+			error = count - buf.ctx.count;
+	}
+	return error;
+}
+
+struct getdents_callback64 {
+	struct dir_context ctx;
+	struct linux_dirent64 __user * current_dir;
+	int prev_reclen;
+	int error;
+};
+
+static bool filldir64(struct dir_context *ctx, const char *name, int namlen,
+		     loff_t offset, u64 ino, unsigned int d_type)
+{
+	struct linux_dirent64 __user *dirent, *prev;
+	struct getdents_callback64 *buf =
+		container_of(ctx, struct getdents_callback64, ctx);
+	int reclen = ALIGN(dirent_size(dirent, namlen + 1), sizeof(u64));
+	int prev_reclen;
+	unsigned int flags = d_type;
+
+	BUILD_BUG_ON(FILLDIR_FLAG_NOINTR & S_DT_MASK);
+	d_type &= S_DT_MASK;
+
+	buf->error = verify_dirent_name(name, namlen);
+	if (unlikely(buf->error))
+		return false;
+	buf->error = -EINVAL;	/* only used if we fail.. */
+	if (reclen > ctx->count)
+		return false;
+	prev_reclen = buf->prev_reclen;
+	if (!(flags & FILLDIR_FLAG_NOINTR) && prev_reclen && signal_pending(current))
+		return false;
+	dirent = buf->current_dir;
+	prev = (void __user *)dirent - prev_reclen;
+	scoped_user_write_access_size(prev, reclen + prev_reclen, efault) {
+		/* This might be 'dirent->d_off', but if so it will get overwritten */
+		unsafe_put_user(offset, &prev->d_off, efault);
+		unsafe_put_user(ino, &dirent->d_ino, efault);
+		unsafe_put_user(reclen, &dirent->d_reclen, efault);
+		unsafe_put_user(d_type, &dirent->d_type, efault);
+		unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault);
+	}
+
+	buf->prev_reclen = reclen;
+	buf->current_dir = (void __user *)dirent + reclen;
+	ctx->count -= reclen;
+	return true;
+
+efault:
+	buf->error = -EFAULT;
+	return false;
+}
+
+SYSCALL_DEFINE3(getdents64, unsigned int, fd,
+		struct linux_dirent64 __user *, dirent, unsigned int, count)
+{
+	CLASS(fd_pos, f)(fd);
+	struct getdents_callback64 buf = {
+		.ctx.actor = filldir64,
+		.ctx.count = count,
+		.ctx.dt_flags_mask = FILLDIR_FLAG_NOINTR,
+		.current_dir = dirent
+	};
+	int error;
+
+	if (fd_empty(f))
+		return -EBADF;
+
+	error = iterate_dir(fd_file(f), &buf.ctx);
+	if (error >= 0)
+		error = buf.error;
+	if (buf.prev_reclen) {
+		struct linux_dirent64 __user * lastdirent;
+		typeof(lastdirent->d_off) d_off = buf.ctx.pos;
+
+		lastdirent = (void __user *) buf.current_dir - buf.prev_reclen;
+		if (put_user(d_off, &lastdirent->d_off))
+			error = -EFAULT;
+		else
+			error = count - buf.ctx.count;
+	}
+	return error;
+}
+
+#ifdef CONFIG_COMPAT
+struct compat_old_linux_dirent {
+	compat_ulong_t	d_ino;
+	compat_ulong_t	d_offset;
+	unsigned short	d_namlen;
+	char		d_name[];
+};
+
+struct compat_readdir_callback {
+	struct dir_context ctx;
+	struct compat_old_linux_dirent __user *dirent;
+	int result;
+};
+
+static bool compat_fillonedir(struct dir_context *ctx, const char *name,
+			     int namlen, loff_t offset, u64 ino,
+			     unsigned int d_type)
+{
+	struct compat_readdir_callback *buf =
+		container_of(ctx, struct compat_readdir_callback, ctx);
+	struct compat_old_linux_dirent __user *dirent;
+	compat_ulong_t d_ino;
+
+	if (buf->result)
+		return false;
+	buf->result = verify_dirent_name(name, namlen);
+	if (buf->result)
+		return false;
+	d_ino = ino;
+	if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
+		buf->result = -EOVERFLOW;
+		return false;
+	}
+	buf->result++;
+	dirent = buf->dirent;
+	scoped_user_write_access_size(dirent, dirent_size(dirent, namlen + 1), efault) {
+		unsafe_put_user(d_ino, &dirent->d_ino, efault);
+		unsafe_put_user(offset, &dirent->d_offset, efault);
+		unsafe_put_user(namlen, &dirent->d_namlen, efault);
+		unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault);
+	}
+	return true;
+efault:
+	buf->result = -EFAULT;
+	return false;
+}
+
+COMPAT_SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
+		struct compat_old_linux_dirent __user *, dirent, unsigned int, count)
+{
+	int error;
+	CLASS(fd_pos, f)(fd);
+	struct compat_readdir_callback buf = {
+		.ctx.actor = compat_fillonedir,
+		.ctx.count = 1, /* Hint to fs: just one entry. */
+		.dirent = dirent
+	};
+
+	if (fd_empty(f))
+		return -EBADF;
+
+	error = iterate_dir(fd_file(f), &buf.ctx);
+	if (buf.result)
+		error = buf.result;
+
+	return error;
+}
+
+struct compat_linux_dirent {
+	compat_ulong_t	d_ino;
+	compat_ulong_t	d_off;
+	unsigned short	d_reclen;
+	char		d_name[];
+};
+
+struct compat_getdents_callback {
+	struct dir_context ctx;
+	struct compat_linux_dirent __user *current_dir;
+	int prev_reclen;
+	int error;
+};
+
+static bool compat_filldir(struct dir_context *ctx, const char *name, int namlen,
+		loff_t offset, u64 ino, unsigned int d_type)
+{
+	struct compat_linux_dirent __user *dirent, *prev;
+	struct compat_getdents_callback *buf =
+		container_of(ctx, struct compat_getdents_callback, ctx);
+	compat_ulong_t d_ino;
+	int reclen = ALIGN(dirent_size(dirent, namlen + 2), sizeof(compat_long_t));
+	int prev_reclen;
+	unsigned int flags = d_type;
+
+	BUILD_BUG_ON(FILLDIR_FLAG_NOINTR & S_DT_MASK);
+	d_type &= S_DT_MASK;
+
+	buf->error = verify_dirent_name(name, namlen);
+	if (unlikely(buf->error))
+		return false;
+	buf->error = -EINVAL;	/* only used if we fail.. */
+	if (reclen > ctx->count)
+		return false;
+	d_ino = ino;
+	if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
+		buf->error = -EOVERFLOW;
+		return false;
+	}
+	prev_reclen = buf->prev_reclen;
+	if (!(flags & FILLDIR_FLAG_NOINTR) && prev_reclen && signal_pending(current))
+		return false;
+	dirent = buf->current_dir;
+	prev = (void __user *) dirent - prev_reclen;
+	scoped_user_write_access_size(prev, reclen + prev_reclen, efault) {
+		unsafe_put_user(offset, &prev->d_off, efault);
+		unsafe_put_user(d_ino, &dirent->d_ino, efault);
+		unsafe_put_user(reclen, &dirent->d_reclen, efault);
+		unsafe_put_user(d_type, (char __user *)dirent + reclen - 1, efault);
+		unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault);
+	}
+
+	buf->prev_reclen = reclen;
+	buf->current_dir = (void __user *)dirent + reclen;
+	ctx->count -= reclen;
+	return true;
+efault:
+	buf->error = -EFAULT;
+	return false;
+}
+
+COMPAT_SYSCALL_DEFINE3(getdents, unsigned int, fd,
+		struct compat_linux_dirent __user *, dirent, unsigned int, count)
+{
+	CLASS(fd_pos, f)(fd);
+	struct compat_getdents_callback buf = {
+		.ctx.actor = compat_filldir,
+		.ctx.count = count,
+		.ctx.dt_flags_mask = FILLDIR_FLAG_NOINTR,
+		.current_dir = dirent,
+	};
+	int error;
+
+	if (fd_empty(f))
+		return -EBADF;
+
+	error = iterate_dir(fd_file(f), &buf.ctx);
+	if (error >= 0)
+		error = buf.error;
+	if (buf.prev_reclen) {
+		struct compat_linux_dirent __user * lastdirent;
+		lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
+
+		if (put_user(buf.ctx.pos, &lastdirent->d_off))
+			error = -EFAULT;
+		else
+			error = count - buf.ctx.count;
+	}
+	return error;
+}
+#endif