From: Alexander Potapenko <glider@google.com>
Date: Mon, 21 Nov 2022 11:21:30 +0000 (+0100)
Subject: fs: ext4: initialize fsdata in pagecache_write()
X-Git-Tag: io_uring-6.2-2022-12-19~66^2~21
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=956510c0c7439e90b8103aaeaf4da92878c622f0;p=linux-block.git

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);