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Date:   Mon, 21 Nov 2022 12:21:30 +0100
Mime-Version: 1.0
Message-ID: <20221121112134.407362-1-glider@google.com>
Subject: [PATCH 1/5] fs: ext4: initialize fsdata in pagecache_write()
From:   Alexander Potapenko <glider@google.com>
To:     glider@google.com
Cc:     linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
        tytso@mit.edu, adilger.kernel@dilger.ca, jaegeuk@kernel.org,
        chao@kernel.org, linux-fsdevel@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
        Eric Biggers <ebiggers@kernel.org>,
        syzbot+9767be679ef5016b6082@syzkaller.appspotmail.com
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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>
---
 fs/ext4/verity.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c
index 3c640bd7ecaeb..30e3b65798b50 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);
-- 
2.38.1.584.g0f3c55d4c2-goog