From: Eric Biggers ebiggers@google.com
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 4ec17d688d74 ("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: 4ec17d688d74 ("f2fs: avoid unneeded initializing when converting inline dentry") Cc: stable@vger.kernel.org # v4.3+ Signed-off-by: Eric Biggers ebiggers@google.com --- fs/f2fs/inline.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c index 08e302d32118d..72269e7efd260 100644 --- a/fs/f2fs/inline.c +++ b/fs/f2fs/inline.c @@ -421,18 +421,17 @@ 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);
base-commit: 7a2b15cfa8dbbd54beb4e2ce7b2f42eb0ad00425