Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 2bef8314 authored by Eric Biggers's avatar Eric Biggers Committed by Greg Kroah-Hartman
Browse files

f2fs: fix information leak in f2fs_move_inline_dirents() 



commit 9a5571cff4ffcfc24847df9fd545cc5799ac0ee5 upstream.

When converting an inline directory to a regular one, f2fs is leaking
uninitialized memory to disk because it doesn't initialize the entire
directory block.  Fix this by zero-initializing the block.

This bug was introduced by commit 4ec17d68 ("f2fs: avoid unneeded
initializing when converting inline dentry"), which didn't consider the
security implications of leaking uninitialized memory to disk.

This was found by running xfstest generic/435 on a KMSAN-enabled kernel.

Fixes: 4ec17d68 ("f2fs: avoid unneeded initializing when converting inline dentry")
Cc: <stable@vger.kernel.org> # v4.3+
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3776ef78

fs/f2fs/inline.c

+6 −7
Original line number Diff line number Diff line
@@ -402,18 +402,17 @@ static int f2fs_move_inline_dirents(struct inode *dir, struct page *ipage, 


	dentry_blk = page_address(page);



	/*

	 * Start by zeroing the full block, to ensure that all unused space is

	 * zeroed and no uninitialized memory is leaked to disk.

	 */

	memset(dentry_blk, 0, F2FS_BLKSIZE);



	make_dentry_ptr_inline(dir, &src, inline_dentry);

	make_dentry_ptr_block(dir, &dst, dentry_blk);



	/* copy data from inline dentry block to new dentry block */

	memcpy(dst.bitmap, src.bitmap, src.nr_bitmap);

	memset(dst.bitmap + src.nr_bitmap, 0, dst.nr_bitmap - src.nr_bitmap);

	/*

	 * we do not need to zero out remainder part of dentry and filename

	 * field, since we have used bitmap for marking the usage status of

	 * them, besides, we can also ignore copying/zeroing reserved space

	 * of dentry block, because them haven't been used so far.

	 */

	memcpy(dst.dentry, src.dentry, SIZE_OF_DIR_ENTRY * src.max);

	memcpy(dst.filename, src.filename, src.max * F2FS_SLOT_LEN);