[PATCH] orangefs: fix out-of-bounds fsid access

[Arnd Bergmann]

From: Arnd Bergmann <arnd@xxxxxxxx>

orangefs_statfs() copies two consecutive fields of the superblock into
the statfs structure, which triggers a warning from the string fortification
helpers:

In file included from fs/orangefs/super.c:8:
include/linux/fortify-string.h:592:4: error: call to '__read_overflow2_field' declared with 'warning' attribute: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
                        __read_overflow2_field(q_size_field, size);

Change the memcpy() to an individual assignment of the two fields, which helps
both the compiler and human readers understand better what it does.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 fs/orangefs/super.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index 5254256a224d7..509a74aca2dcb 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -201,7 +201,10 @@ static int orangefs_statfs(struct dentry *dentry, struct kstatfs *buf)
 		     (long)new_op->downcall.resp.statfs.files_avail);
 
 	buf->f_type = sb->s_magic;
-	memcpy(&buf->f_fsid, &ORANGEFS_SB(sb)->fs_id, sizeof(buf->f_fsid));
+	buf->f_fsid = (__kernel_fsid_t) {{
+		ORANGEFS_SB(sb)->fs_id,
+		ORANGEFS_SB(sb)->id,
+	}};
 	buf->f_bsize = new_op->downcall.resp.statfs.block_size;
 	buf->f_namelen = ORANGEFS_NAME_MAX;
 
-- 
2.39.2