FAILED: patch "[PATCH] nilfs2: fix kernel bug on rename operation of broken" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x a9e1ddc09ca55746079cc479aa3eb6411f0d99d4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024071537-wilt-goliath-e654@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

a9e1ddc09ca5 ("nilfs2: fix kernel bug on rename operation of broken directory") 6f133c97e5ce ("nilfs2: convert nilfs_rename() to use folios")
a4bf041e44d5 ("nilfs2: convert nilfs_find_entry to use a folio") 9b77f66f9927 ("nilfs2: switch to kmap_local for directory handling") 09a46acb3697 ("nilfs2: return the mapped address from nilfs_get_page()") 6af2191f8358 ("nilfs2: remove page_address() from nilfs_delete_entry") 6bb09fa1b44f ("nilfs2: remove page_address() from nilfs_set_link") 8cf57c6df818 ("nilfs2: eliminate staggered calls to kunmap in nilfs_rename") 584db20c181f ("nilfs2: move page release outside of nilfs_delete_entry and nilfs_set_link") b3e1cc3935ff ("nilfs2: convert to new timestamp accessors")
e21d4f419402 ("nilfs2: convert to ctime accessor functions")
21a87d88c225 ("nilfs2: fix NULL pointer dereference at nilfs_bmap_lookup_at_level()") 79ea65563ad8 ("nilfs2: Remove check for PageError")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a9e1ddc09ca55746079cc479aa3eb6411f0d99d4 Mon Sep 17 00:00:00 2001
From: Ryusuke Konishi <[email protected]>
Date: Sat, 29 Jun 2024 01:51:07 +0900
Subject: [PATCH] nilfs2: fix kernel bug on rename operation of broken
directory

Syzbot reported that in rename directory operation on broken directory on nilfs2, __block_write_begin_int() called to prepare block write may fail BUG_ON check for access exceeding the folio/page size.

This is because nilfs_dotdot(), which gets parent directory reference entry ("..") of the directory to be moved or renamed, does not check consistency enough, and may return location exceeding folio/page size for broken directories.

Fix this issue by checking required directory entries ("." and "..") in the first chunk of the directory in nilfs_dotdot().

index dddfa604491a..4a29b0138d75 100644
@@ -383,11 +383,39 @@ struct nilfs_dir_entry *nilfs_find_entry(struct inode *dir,
 
 struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct folio **foliop)
 {
-	struct nilfs_dir_entry *de = nilfs_get_folio(dir, 0, foliop);
+	struct folio *folio;
+	struct nilfs_dir_entry *de, *next_de;
+	size_t limit;
+	char *msg;
 
+	de = nilfs_get_folio(dir, 0, &folio);
 	if (IS_ERR(de))
 		return NULL;
-	return nilfs_next_entry(de);
+
+	limit = nilfs_last_byte(dir, 0);  /* is a multiple of chunk size */
+	if (unlikely(!limit || le64_to_cpu(de->inode) != dir->i_ino ||
+		     !nilfs_match(1, ".", de))) {
+		msg = "missing '.'";
+		goto fail;
+	}
+
+	next_de = nilfs_next_entry(de);
+	/*
+	 * If "next_de" has not reached the end of the chunk, there is
+	 * at least one more record.  Check whether it matches "..".
+	 */
+	if (unlikely((char *)next_de == (char *)de + nilfs_chunk_size(dir) ||
+		     !nilfs_match(2, "..", next_de))) {
+		msg = "missing '..'";
+		goto fail;
+	}
+	*foliop = folio;
+	return next_de;
+
+fail:
+	nilfs_error(dir->i_sb, "directory #%lu %s", dir->i_ino, msg);
+	folio_release_kmap(folio, de);
+	return NULL;
 }
 
 ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)