libext2fs: zero the EA block buffer before filling it

When writing an extended attribute (EA) block, it's quite possible
that the EA formatting code will not write the entire buffer.
Therefore, we must zero the buffer beforehand to avoid writing random
heap contents to disk.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reported-by: Sami Liedes <sami.liedes@iki.fi>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
index b52abb5..c397e00 100644 (file)
--- a/lib/ext2fs/ext_attr.c
+++ b/lib/ext2fs/ext_attr.c
@@ -550,7 +550,7 @@ errcode_t ext2fs_xattrs_write(struct ext2_xattr_handle *handle)
 
 write_ea_block:
        /* Write the EA block */
-       err = ext2fs_get_mem(handle->fs->blocksize, &block_buf);
+       err = ext2fs_get_memzero(handle->fs->blocksize, &block_buf);
        if (err)
                goto out;