FAILED: patch "[PATCH] fs: ext4: initialize fsdata in pagecache_write()" failed to apply to 5.4-stable tree

FAILED: patch "[PATCH] fs: ext4: initialize fsdata in pagecache_write()" failed to apply to 5.4-stable tree

[gregkh]

The patch below does not apply to the 5.4-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 <stable@vger.kernel.org>.

Possible dependencies:

956510c0c743 ("fs: ext4: initialize fsdata in pagecache_write()")
bd256fda92ef ("ext4: use memcpy_to_page() in pagecache_write()")

thanks,

greg k-h

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

From 956510c0c7439e90b8103aaeaf4da92878c622f0 Mon Sep 17 00:00:00 2001
From: Alexander Potapenko <glider@google.com>
Date: Mon, 21 Nov 2022 12:21:30 +0100
Subject: [PATCH] fs: ext4: initialize fsdata in pagecache_write()

When aops->write_begin() does not initialize fsdata, KMSAN reports
an error passing the latter to aops->write_end().

Fix this by unconditionally initializing fsdata.

Cc: Eric Biggers <ebiggers@kernel.org>
Fixes: c93d8f885809 ("ext4: add basic fs-verity support")
Reported-by: syzbot+9767be679ef5016b6082@syzkaller.appspotmail.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221121112134.407362-1-glider@google.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c
index 3c640bd7ecae..30e3b65798b5 100644
--- a/fs/ext4/verity.c
+++ b/fs/ext4/verity.c
@@ -79,7 +79,7 @@ static int pagecache_write(struct inode *inode, const void *buf, size_t count,
 		size_t n = min_t(size_t, count,
 				 PAGE_SIZE - offset_in_page(pos));
 		struct page *page;
-		void *fsdata;
+		void *fsdata = NULL;
 		int res;
 
 		res = aops->write_begin(NULL, mapping, pos, n, &page, &fsdata);