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, 386 insertions, 0 deletions

diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
new file mode 100644
index 000000000..c7b6cdb2e
--- /dev/null
+++ b/fs/ext4/readpage.c
@@ -0,0 +1,386 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/ext4/readpage.c
+ *
+ * Copyright (C) 2002, Linus Torvalds.
+ * Copyright (C) 2015, Google, Inc.
+ *
+ * This was originally taken from fs/mpage.c
+ *
+ * The ext4_mpage_readpages() function here is intended to
+ * replace mpage_readahead() in the general case, not just for
+ * encrypted files.  It has some limitations (see below), where it
+ * will fall back to read_block_full_page(), but these limitations
+ * should only be hit when page_size != block_size.
+ *
+ * This will allow us to attach a callback function to support ext4
+ * encryption.
+ *
+ * If anything unusual happens, such as:
+ *
+ * - encountering a page which has buffers
+ * - encountering a page which has a non-hole after a hole
+ * - encountering a page with non-contiguous blocks
+ *
+ * then this code just gives up and calls the buffer_head-based read function.
+ * It does handle a page which has holes at the end - that is a common case:
+ * the end-of-file on blocksize < PAGE_SIZE setups.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/kdev_t.h>
+#include <linux/gfp.h>
+#include <linux/bio.h>
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/blk-crypto.h>
+#include <linux/blkdev.h>
+#include <linux/highmem.h>
+#include <linux/prefetch.h>
+#include <linux/mpage.h>
+#include <linux/writeback.h>
+#include <linux/backing-dev.h>
+
+#include "ext4.h"
+#include <trace/events/ext4.h>
+
+#define NUM_VERITY_WORKS 128
+
+static struct kmem_cache *ext4_verity_work_cache;
+static mempool_t *ext4_verity_work_pool;
+
+struct ext4_verity_work {
+	struct bio *bio;
+	struct fsverity_info *vi;
+	struct work_struct work;
+};
+
+static void __read_end_io(struct bio *bio)
+{
+	struct folio_iter fi;
+
+	bio_for_each_folio_all(fi, bio)
+		folio_end_read(fi.folio, bio->bi_status == 0);
+	if (bio->bi_private)
+		mempool_free(bio->bi_private, ext4_verity_work_pool);
+	bio_put(bio);
+}
+
+static void verity_work(struct work_struct *work)
+{
+	struct ext4_verity_work *ctx =
+		container_of(work, struct ext4_verity_work, work);
+	struct bio *bio = ctx->bio;
+	struct fsverity_info *vi = ctx->vi;
+
+	/*
+	 * Free the ext4_verity_work right away, since it's no longer needed.
+	 * This relieves the pressure on the mempool as much as possible.
+	 */
+	mempool_free(ctx, ext4_verity_work_pool);
+	bio->bi_private = NULL;
+
+	fsverity_verify_bio(vi, bio);
+
+	__read_end_io(bio);
+}
+
+/*
+ * I/O completion handler for multipage BIOs.
+ *
+ * The mpage code never puts partial pages into a BIO (except for end-of-file).
+ * If a page does not map to a contiguous run of blocks then it simply falls
+ * back to block_read_full_folio().
+ *
+ * Why is this?  If a page's completion depends on a number of different BIOs
+ * which can complete in any order (or at the same time) then determining the
+ * status of that page is hard.  See end_buffer_async_read() for the details.
+ * There is no point in duplicating all that complexity.
+ */
+static void mpage_end_io(struct bio *bio)
+{
+	if (IS_ENABLED(CONFIG_FS_VERITY) && bio->bi_private &&
+	    !bio->bi_status) {
+		struct ext4_verity_work *ctx = bio->bi_private;
+
+		INIT_WORK(&ctx->work, verity_work);
+		fsverity_enqueue_verify_work(&ctx->work);
+		return;
+	}
+	__read_end_io(bio);
+}
+
+static void ext4_set_verity_work(struct bio *bio, struct fsverity_info *vi)
+{
+	if (vi) {
+		/* Due to the mempool, this never fails. */
+		struct ext4_verity_work *ctx =
+			mempool_alloc(ext4_verity_work_pool, GFP_NOFS);
+
+		ctx->bio = bio;
+		ctx->vi = vi;
+		bio->bi_private = ctx;
+	}
+}
+
+static inline loff_t ext4_readpage_limit(struct inode *inode)
+{
+	if (IS_ENABLED(CONFIG_FS_VERITY) && IS_VERITY(inode))
+		return inode->i_sb->s_maxbytes;
+
+	return i_size_read(inode);
+}
+
+static int ext4_mpage_readpages(struct inode *inode, struct fsverity_info *vi,
+		struct readahead_control *rac, struct folio *folio)
+{
+	struct bio *bio = NULL;
+	sector_t last_block_in_bio = 0;
+	const unsigned blkbits = inode->i_blkbits;
+	const unsigned blocksize = 1 << blkbits;
+	sector_t block_in_file;
+	sector_t last_block;
+	sector_t last_block_in_file;
+	sector_t first_block;
+	loff_t pos;
+	unsigned page_block;
+	struct block_device *bdev = inode->i_sb->s_bdev;
+	int length;
+	unsigned relative_block = 0;
+	struct ext4_map_blocks map;
+	unsigned int nr_pages, folio_pages;
+
+	map.m_pblk = 0;
+	map.m_lblk = 0;
+	map.m_len = 0;
+	map.m_flags = 0;
+
+	nr_pages = rac ? readahead_count(rac) : folio_nr_pages(folio);
+	for (; nr_pages; nr_pages -= folio_pages) {
+		int fully_mapped = 1;
+		unsigned int first_hole;
+		unsigned int blocks_per_folio;
+
+		if (rac)
+			folio = readahead_folio(rac);
+
+		folio_pages = folio_nr_pages(folio);
+		prefetchw(&folio->flags);
+
+		if (folio_buffers(folio))
+			goto confused;
+
+		blocks_per_folio = folio_size(folio) >> blkbits;
+		first_hole = blocks_per_folio;
+		pos = folio_pos(folio);
+		block_in_file = pos >> blkbits;
+		last_block = EXT4_PG_TO_LBLK(inode, folio->index + nr_pages);
+		last_block_in_file = (ext4_readpage_limit(inode) +
+				      blocksize - 1) >> blkbits;
+		if (last_block > last_block_in_file)
+			last_block = last_block_in_file;
+		page_block = 0;
+
+		/*
+		 * Map blocks using the previous result first.
+		 */
+		if ((map.m_flags & EXT4_MAP_MAPPED) &&
+		    block_in_file > map.m_lblk &&
+		    block_in_file < (map.m_lblk + map.m_len)) {
+			unsigned map_offset = block_in_file - map.m_lblk;
+			unsigned last = map.m_len - map_offset;
+
+			first_block = map.m_pblk + map_offset;
+			for (relative_block = 0; ; relative_block++) {
+				if (relative_block == last) {
+					/* needed? */
+					map.m_flags &= ~EXT4_MAP_MAPPED;
+					break;
+				}
+				if (page_block == blocks_per_folio)
+					break;
+				page_block++;
+				block_in_file++;
+			}
+		}
+
+		/*
+		 * Then do more ext4_map_blocks() calls until we are
+		 * done with this folio.
+		 */
+		while (page_block < blocks_per_folio) {
+			if (block_in_file < last_block) {
+				map.m_lblk = block_in_file;
+				map.m_len = last_block - block_in_file;
+
+				if (ext4_map_blocks(NULL, inode, &map, 0) < 0) {
+				set_error_page:
+					folio_zero_segment(folio, 0,
+							  folio_size(folio));
+					folio_unlock(folio);
+					goto next_page;
+				}
+			}
+			if ((map.m_flags & EXT4_MAP_MAPPED) == 0) {
+				fully_mapped = 0;
+				if (first_hole == blocks_per_folio)
+					first_hole = page_block;
+				page_block++;
+				block_in_file++;
+				continue;
+			}
+			if (first_hole != blocks_per_folio)
+				goto confused;		/* hole -> non-hole */
+
+			/* Contiguous blocks? */
+			if (!page_block)
+				first_block = map.m_pblk;
+			else if (first_block + page_block != map.m_pblk)
+				goto confused;
+			for (relative_block = 0; ; relative_block++) {
+				if (relative_block == map.m_len) {
+					/* needed? */
+					map.m_flags &= ~EXT4_MAP_MAPPED;
+					break;
+				} else if (page_block == blocks_per_folio)
+					break;
+				page_block++;
+				block_in_file++;
+			}
+		}
+		if (first_hole != blocks_per_folio) {
+			folio_zero_segment(folio, first_hole << blkbits,
+					  folio_size(folio));
+			if (first_hole == 0) {
+				if (vi && !fsverity_verify_folio(vi, folio))
+					goto set_error_page;
+				folio_end_read(folio, true);
+				continue;
+			}
+		} else if (fully_mapped) {
+			folio_set_mappedtodisk(folio);
+		}
+
+		/*
+		 * This folio will go to BIO.  Do we need to send this
+		 * BIO off first?
+		 */
+		if (bio && (last_block_in_bio != first_block - 1 ||
+			    !fscrypt_mergeable_bio(bio, inode, pos))) {
+		submit_and_realloc:
+			blk_crypto_submit_bio(bio);
+			bio = NULL;
+		}
+		if (bio == NULL) {
+			/*
+			 * bio_alloc will _always_ be able to allocate a bio if
+			 * __GFP_DIRECT_RECLAIM is set, see bio_alloc_bioset().
+			 */
+			bio = bio_alloc(bdev, bio_max_segs(nr_pages),
+					REQ_OP_READ, GFP_KERNEL);
+			fscrypt_set_bio_crypt_ctx(bio, inode, pos, GFP_KERNEL);
+			ext4_set_verity_work(bio, vi);
+			bio->bi_iter.bi_sector = first_block << (blkbits - 9);
+			bio->bi_end_io = mpage_end_io;
+			if (rac)
+				bio->bi_opf |= REQ_RAHEAD;
+		}
+
+		length = first_hole << blkbits;
+		if (!bio_add_folio(bio, folio, length, 0))
+			goto submit_and_realloc;
+
+		if (((map.m_flags & EXT4_MAP_BOUNDARY) &&
+		     (relative_block == map.m_len)) ||
+		    (first_hole != blocks_per_folio)) {
+			blk_crypto_submit_bio(bio);
+			bio = NULL;
+		} else
+			last_block_in_bio = first_block + blocks_per_folio - 1;
+		continue;
+	confused:
+		if (bio) {
+			blk_crypto_submit_bio(bio);
+			bio = NULL;
+		}
+		if (!folio_test_uptodate(folio))
+			block_read_full_folio(folio, ext4_get_block);
+		else
+			folio_unlock(folio);
+next_page:
+		; /* A label shall be followed by a statement until C23 */
+	}
+	if (bio)
+		blk_crypto_submit_bio(bio);
+	return 0;
+}
+
+int ext4_read_folio(struct file *file, struct folio *folio)
+{
+	struct inode *inode = folio->mapping->host;
+	struct fsverity_info *vi = NULL;
+	int ret;
+
+	trace_ext4_read_folio(inode, folio);
+
+	if (ext4_has_inline_data(inode)) {
+		ret = ext4_readpage_inline(inode, folio);
+		if (ret != -EAGAIN)
+			return ret;
+	}
+
+	if (folio->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE))
+		vi = fsverity_get_info(inode);
+	if (vi)
+		fsverity_readahead(vi, folio->index, folio_nr_pages(folio));
+	return ext4_mpage_readpages(inode, vi, NULL, folio);
+}
+
+void ext4_readahead(struct readahead_control *rac)
+{
+	struct inode *inode = rac->mapping->host;
+	struct fsverity_info *vi = NULL;
+
+	/* If the file has inline data, no need to do readahead. */
+	if (ext4_has_inline_data(inode))
+		return;
+
+	if (readahead_index(rac) < DIV_ROUND_UP(inode->i_size, PAGE_SIZE))
+		vi = fsverity_get_info(inode);
+	if (vi)
+		fsverity_readahead(vi, readahead_index(rac),
+				   readahead_count(rac));
+	ext4_mpage_readpages(inode, vi, rac, NULL);
+}
+
+int __init ext4_init_verity_caches(void)
+{
+	if (!IS_ENABLED(CONFIG_FS_VERITY))
+		return 0;
+	ext4_verity_work_cache =
+		KMEM_CACHE(ext4_verity_work, SLAB_RECLAIM_ACCOUNT);
+
+	if (!ext4_verity_work_cache)
+		goto fail;
+	ext4_verity_work_pool = mempool_create_slab_pool(
+		NUM_VERITY_WORKS, ext4_verity_work_cache);
+	if (!ext4_verity_work_pool)
+		goto fail_free_cache;
+	return 0;
+
+fail_free_cache:
+	kmem_cache_destroy(ext4_verity_work_cache);
+fail:
+	return -ENOMEM;
+}
+
+void ext4_exit_verity_caches(void)
+{
+	if (!IS_ENABLED(CONFIG_FS_VERITY))
+		return;
+	mempool_destroy(ext4_verity_work_pool);
+	kmem_cache_destroy(ext4_verity_work_cache);
+}