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);