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, 301 insertions, 0 deletions

diff --git a/fs/fat/nfs.c b/fs/fat/nfs.c
new file mode 100644
index 000000000..6e1b37171
--- /dev/null
+++ b/fs/fat/nfs.c
@@ -0,0 +1,301 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* fs/fat/nfs.c
+ */
+
+#include <linux/exportfs.h>
+#include "fat.h"
+
+struct fat_fid {
+	u32 i_gen;
+	u32 i_pos_low;
+	u16 i_pos_hi;
+	u16 parent_i_pos_hi;
+	u32 parent_i_pos_low;
+	u32 parent_i_gen;
+};
+
+#define FAT_FID_SIZE_WITHOUT_PARENT 3
+#define FAT_FID_SIZE_WITH_PARENT (sizeof(struct fat_fid)/sizeof(u32))
+
+/*
+ * Look up a directory inode given its starting cluster.
+ */
+static struct inode *fat_dget(struct super_block *sb, int i_logstart)
+{
+	struct msdos_sb_info *sbi = MSDOS_SB(sb);
+	struct hlist_head *head;
+	struct msdos_inode_info *i;
+	struct inode *inode = NULL;
+
+	head = sbi->dir_hashtable + fat_dir_hash(i_logstart);
+	spin_lock(&sbi->dir_hash_lock);
+	hlist_for_each_entry(i, head, i_dir_hash) {
+		BUG_ON(i->vfs_inode.i_sb != sb);
+		if (i->i_logstart != i_logstart)
+			continue;
+		inode = igrab(&i->vfs_inode);
+		if (inode)
+			break;
+	}
+	spin_unlock(&sbi->dir_hash_lock);
+	return inode;
+}
+
+static struct inode *fat_ilookup(struct super_block *sb, u64 ino, loff_t i_pos)
+{
+	if (MSDOS_SB(sb)->options.nfs == FAT_NFS_NOSTALE_RO)
+		return fat_iget(sb, i_pos);
+
+	else {
+		if ((ino < MSDOS_ROOT_INO) || (ino == MSDOS_FSINFO_INO))
+			return NULL;
+		return ilookup(sb, ino);
+	}
+}
+
+static struct inode *__fat_nfs_get_inode(struct super_block *sb,
+				       u64 ino, u32 generation, loff_t i_pos)
+{
+	struct inode *inode = fat_ilookup(sb, ino, i_pos);
+
+	if (inode && generation && (inode->i_generation != generation)) {
+		iput(inode);
+		inode = NULL;
+	}
+	if (inode == NULL && MSDOS_SB(sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
+		struct buffer_head *bh = NULL;
+		struct msdos_dir_entry *de ;
+		sector_t blocknr;
+		int offset;
+		fat_get_blknr_offset(MSDOS_SB(sb), i_pos, &blocknr, &offset);
+		bh = sb_bread(sb, blocknr);
+		if (!bh) {
+			fat_msg(sb, KERN_ERR,
+				"unable to read block(%llu) for building NFS inode",
+				(llu)blocknr);
+			return inode;
+		}
+		de = (struct msdos_dir_entry *)bh->b_data;
+		/* If a file is deleted on server and client is not updated
+		 * yet, we must not build the inode upon a lookup call.
+		 */
+		if (IS_FREE(de[offset].name))
+			inode = NULL;
+		else
+			inode = fat_build_inode(sb, &de[offset], i_pos);
+		brelse(bh);
+	}
+
+	return inode;
+}
+
+static struct inode *fat_nfs_get_inode(struct super_block *sb,
+				       u64 ino, u32 generation)
+{
+
+	return __fat_nfs_get_inode(sb, ino, generation, 0);
+}
+
+static int
+fat_encode_fh_nostale(struct inode *inode, __u32 *fh, int *lenp,
+		      struct inode *parent)
+{
+	int len = *lenp;
+	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+	struct fat_fid *fid = (struct fat_fid *) fh;
+	loff_t i_pos;
+	int type = FILEID_FAT_WITHOUT_PARENT;
+
+	if (parent) {
+		if (len < FAT_FID_SIZE_WITH_PARENT) {
+			*lenp = FAT_FID_SIZE_WITH_PARENT;
+			return FILEID_INVALID;
+		}
+	} else {
+		if (len < FAT_FID_SIZE_WITHOUT_PARENT) {
+			*lenp = FAT_FID_SIZE_WITHOUT_PARENT;
+			return FILEID_INVALID;
+		}
+	}
+
+	i_pos = fat_i_pos_read(sbi, inode);
+	*lenp = FAT_FID_SIZE_WITHOUT_PARENT;
+	fid->i_gen = inode->i_generation;
+	fid->i_pos_low = i_pos & 0xFFFFFFFF;
+	fid->i_pos_hi = (i_pos >> 32) & 0xFFFF;
+	if (parent) {
+		i_pos = fat_i_pos_read(sbi, parent);
+		fid->parent_i_pos_hi = (i_pos >> 32) & 0xFFFF;
+		fid->parent_i_pos_low = i_pos & 0xFFFFFFFF;
+		fid->parent_i_gen = parent->i_generation;
+		type = FILEID_FAT_WITH_PARENT;
+		*lenp = FAT_FID_SIZE_WITH_PARENT;
+	} else {
+		/*
+		 * We need to initialize this field because the fh is actually
+		 * 12 bytes long
+		 */
+		fid->parent_i_pos_hi = 0;
+	}
+
+	return type;
+}
+
+/*
+ * Map a NFS file handle to a corresponding dentry.
+ * The dentry may or may not be connected to the filesystem root.
+ */
+static struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
+				int fh_len, int fh_type)
+{
+	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+				    fat_nfs_get_inode);
+}
+
+static struct dentry *fat_fh_to_dentry_nostale(struct super_block *sb,
+					       struct fid *fh, int fh_len,
+					       int fh_type)
+{
+	struct inode *inode = NULL;
+	struct fat_fid *fid = (struct fat_fid *)fh;
+	loff_t i_pos;
+
+	switch (fh_type) {
+	case FILEID_FAT_WITHOUT_PARENT:
+		if (fh_len < FAT_FID_SIZE_WITHOUT_PARENT)
+			return NULL;
+		break;
+	case FILEID_FAT_WITH_PARENT:
+		if (fh_len < FAT_FID_SIZE_WITH_PARENT)
+			return NULL;
+		break;
+	default:
+		return NULL;
+	}
+	i_pos = fid->i_pos_hi;
+	i_pos = (i_pos << 32) | (fid->i_pos_low);
+	inode = __fat_nfs_get_inode(sb, 0, fid->i_gen, i_pos);
+
+	return d_obtain_alias(inode);
+}
+
+/*
+ * Find the parent for a file specified by NFS handle.
+ * This requires that the handle contain the i_ino of the parent.
+ */
+static struct dentry *fat_fh_to_parent(struct super_block *sb, struct fid *fid,
+				int fh_len, int fh_type)
+{
+	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+				    fat_nfs_get_inode);
+}
+
+static struct dentry *fat_fh_to_parent_nostale(struct super_block *sb,
+					       struct fid *fh, int fh_len,
+					       int fh_type)
+{
+	struct inode *inode = NULL;
+	struct fat_fid *fid = (struct fat_fid *)fh;
+	loff_t i_pos;
+
+	if (fh_len < FAT_FID_SIZE_WITH_PARENT)
+		return NULL;
+
+	switch (fh_type) {
+	case FILEID_FAT_WITH_PARENT:
+		i_pos = fid->parent_i_pos_hi;
+		i_pos = (i_pos << 32) | (fid->parent_i_pos_low);
+		inode = __fat_nfs_get_inode(sb, 0, fid->parent_i_gen, i_pos);
+		break;
+	}
+
+	return d_obtain_alias(inode);
+}
+
+/*
+ * Rebuild the parent for a directory that is not connected
+ *  to the filesystem root
+ */
+static
+struct inode *fat_rebuild_parent(struct super_block *sb, int parent_logstart)
+{
+	int search_clus, clus_to_match;
+	struct msdos_dir_entry *de;
+	struct inode *parent = NULL;
+	struct inode *dummy_grand_parent = NULL;
+	struct fat_slot_info sinfo;
+	struct msdos_sb_info *sbi = MSDOS_SB(sb);
+	sector_t blknr = fat_clus_to_blknr(sbi, parent_logstart);
+	struct buffer_head *parent_bh = sb_bread(sb, blknr);
+	if (!parent_bh) {
+		fat_msg(sb, KERN_ERR,
+			"unable to read cluster of parent directory");
+		return NULL;
+	}
+
+	de = (struct msdos_dir_entry *) parent_bh->b_data;
+	clus_to_match = fat_get_start(sbi, &de[0]);
+	search_clus = fat_get_start(sbi, &de[1]);
+
+	dummy_grand_parent = fat_dget(sb, search_clus);
+	if (!dummy_grand_parent) {
+		dummy_grand_parent = new_inode(sb);
+		if (!dummy_grand_parent) {
+			brelse(parent_bh);
+			return parent;
+		}
+
+		dummy_grand_parent->i_ino = iunique(sb, MSDOS_ROOT_INO);
+		fat_fill_inode(dummy_grand_parent, &de[1]);
+		MSDOS_I(dummy_grand_parent)->i_pos = -1;
+	}
+
+	if (!fat_scan_logstart(dummy_grand_parent, clus_to_match, &sinfo)) {
+		parent = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
+		brelse(sinfo.bh);
+	}
+
+	brelse(parent_bh);
+	iput(dummy_grand_parent);
+
+	return parent;
+}
+
+/*
+ * Find the parent for a directory that is not currently connected to
+ * the filesystem root.
+ *
+ * On entry, the caller holds d_inode(child_dir)->i_mutex.
+ */
+static struct dentry *fat_get_parent(struct dentry *child_dir)
+{
+	struct super_block *sb = child_dir->d_sb;
+	struct buffer_head *bh = NULL;
+	struct msdos_dir_entry *de;
+	struct inode *parent_inode = NULL;
+	struct msdos_sb_info *sbi = MSDOS_SB(sb);
+
+	if (!fat_get_dotdot_entry(d_inode(child_dir), &bh, &de)) {
+		int parent_logstart = fat_get_start(sbi, de);
+		parent_inode = fat_dget(sb, parent_logstart);
+		if (!parent_inode && sbi->options.nfs == FAT_NFS_NOSTALE_RO)
+			parent_inode = fat_rebuild_parent(sb, parent_logstart);
+	}
+	brelse(bh);
+
+	return d_obtain_alias(parent_inode);
+}
+
+const struct export_operations fat_export_ops = {
+	.encode_fh	= generic_encode_ino32_fh,
+	.fh_to_dentry   = fat_fh_to_dentry,
+	.fh_to_parent   = fat_fh_to_parent,
+	.get_parent     = fat_get_parent,
+};
+
+const struct export_operations fat_export_ops_nostale = {
+	.encode_fh      = fat_encode_fh_nostale,
+	.fh_to_dentry   = fat_fh_to_dentry_nostale,
+	.fh_to_parent   = fat_fh_to_parent_nostale,
+	.get_parent     = fat_get_parent,
+};