linux-ext4 - [PATCH] fs: ext4: initialize fsdata in pagecache

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Date:   Mon, 14 Nov 2022 09:29:35 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     glider@...gle.com
Cc:     linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        tytso@....edu, adilger.kernel@...ger.ca, jaegeuk@...nel.org,
        chao@...nel.org, linux-fsdevel@...r.kernel.org,
        linux-ext4@...r.kernel.org, Eric Biggers <ebiggers@...nel.org>,
        syzbot+9767be679ef5016b6082@...kaller.appspotmail.com
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.

Also speculatively fix similar issues in affs, f2fs, hfs, hfsplus,
as suggested by Eric Biggers.

Cc: Eric Biggers <ebiggers@...nel.org>
Fixes: c93d8f885809 ("ext4: add basic fs-verity support")
Reported-by: syzbot+9767be679ef5016b6082@...kaller.appspotmail.com
Signed-off-by: Alexander Potapenko <glider@...gle.com>
---
 fs/affs/file.c       | 2 +-
 fs/ext4/verity.c     | 2 +-
 fs/f2fs/verity.c     | 2 +-
 fs/hfs/extent.c      | 2 +-
 fs/hfsplus/extents.c | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/affs/file.c b/fs/affs/file.c
index cefa222f7881c..8daeed31e1af9 100644
--- a/fs/affs/file.c
+++ b/fs/affs/file.c
@@ -880,7 +880,7 @@ affs_truncate(struct inode *inode)
 	if (inode->i_size > AFFS_I(inode)->mmu_private) {
 		struct address_space *mapping = inode->i_mapping;
 		struct page *page;
-		void *fsdata;
+		void *fsdata = NULL;
 		loff_t isize = inode->i_size;
 		int res;
 
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);
diff --git a/fs/f2fs/verity.c b/fs/f2fs/verity.c
index c352fff88a5e6..3f4f3295f1c66 100644
--- a/fs/f2fs/verity.c
+++ b/fs/f2fs/verity.c
@@ -81,7 +81,7 @@ 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);
diff --git a/fs/hfs/extent.c b/fs/hfs/extent.c
index 3f7e9bef98743..6d1878b99b305 100644
--- a/fs/hfs/extent.c
+++ b/fs/hfs/extent.c
@@ -486,7 +486,7 @@ void hfs_file_truncate(struct inode *inode)
 		inode->i_size);
 	if (inode->i_size > HFS_I(inode)->phys_size) {
 		struct address_space *mapping = inode->i_mapping;
-		void *fsdata;
+		void *fsdata = NULL;
 		struct page *page;
 
 		/* XXX: Can use generic_cont_expand? */
diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c
index 721f779b4ec3e..7a542f3dbe502 100644
--- a/fs/hfsplus/extents.c
+++ b/fs/hfsplus/extents.c
@@ -554,7 +554,7 @@ void hfsplus_file_truncate(struct inode *inode)
 	if (inode->i_size > hip->phys_size) {
 		struct address_space *mapping = inode->i_mapping;
 		struct page *page;
-		void *fsdata;
+		void *fsdata = NULL;
 		loff_t size = inode->i_size;
 
 		res = hfsplus_write_begin(NULL, mapping, size, 0,
-- 
2.38.1.431.g37b22c650d-goog