f2fs: fix to avoid memory leakage in f2fs_listxattr

f2fs: fix to avoid memory leakage in f2fs_listxattr

commit 688078e7f36c293dae25b338ddc9e0a2790f6e06 upstream.

In f2fs_listxattr, there is no boundary check before
memcpy e_name to buffer.
If the e_name_len is corrupted,
unexpected memory contents may be returned to the buffer.

Signed-off-by: Randall Huang <huangrandall@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
[bwh: Backported to 4.19: Use f2fs_msg() instead of f2fs_err()]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>