scoutfs: Ensure padding in structs remains zeroed

Audit code for structs allocated on stack without initialization, or
using kmalloc() instead of kzalloc().

- avl.c: zero padding in avl_node on insert.
- btree.c: Verify item padding is zero, or WARN_ONCE.
- inode.c: scoutfs_inode contains scoutfs_timespecs, which have padding.
- net.c: zero pad in net header.
- net.h: scoutfs_net_addr has padding, zero it in scoutfs_addr_from_sin().
- xattr.c: scoutfs_xattr has padding, zero it.
- forest.c: item_root in forest_next_hint() appears to either be
    assigned-to or unused, so no need to zero it.
- key.h: Ensure padding is zeroed in scoutfs_key_set_{zeros,ones}

Signed-off-by: Andy Grover <agrover@versity.com>

kmod/src/avl.c

@@ -11,6 +11,7 @@
  * General Public License for more details.
  */
 #include <linux/kernel.h>
+#include <linux/string.h>
 
 #include "format.h"
 #include "avl.h"
@@ -274,6 +275,7 @@ void scoutfs_avl_insert(struct scoutfs_avl_root *root,
 	node->left = 0;
 	node->right = 0;
 	set_height(root, node);
+	memset(node->__pad, 0, sizeof(node->__pad));
 
 	if (parent == NULL) {
 		root->node = node_off(root, node);

kmod/src/btree.c

@@ -1003,6 +1003,7 @@ static bool bad_avl_node_off(__le16 node_off, int nr)
  *  - values don't overlap each other
  *  - last_free_offset is in fact last free region
  *  - call after leaf modification
+ *  - padding is zero
  */
 static void verify_btree_block(struct super_block *sb,
 			       struct scoutfs_btree_block *bt, int level,
@@ -1017,6 +1018,7 @@ static void verify_btree_block(struct super_block *sb,
 	int end_off;
 	int tot = 0;
 	int i = 0;
+	int j = 0;
 	int nr;
 
 	if (bt->level != level) {
@@ -1055,6 +1057,10 @@ static void verify_btree_block(struct super_block *sb,
 			goto out;
 		}
 
+		for (j = 0; j < sizeof(item->__pad); j++) {
+			WARN_ON_ONCE(item->__pad[j] != 0);
+		}
+
 		if (scoutfs_key_compare(&item->key, start) < 0 ||
 		    scoutfs_key_compare(&item->key, end) > 0) {
 			reason = "item key out of parent range";

kmod/src/inode.c

@@ -719,10 +719,13 @@ static void store_inode(struct scoutfs_inode *cinode, struct inode *inode)
 	cinode->rdev = cpu_to_le32(inode->i_rdev);
 	cinode->atime.sec = cpu_to_le64(inode->i_atime.tv_sec);
 	cinode->atime.nsec = cpu_to_le32(inode->i_atime.tv_nsec);
+	memset(cinode->atime.__pad, 0, sizeof(cinode->atime.__pad));
 	cinode->ctime.sec = cpu_to_le64(inode->i_ctime.tv_sec);
 	cinode->ctime.nsec = cpu_to_le32(inode->i_ctime.tv_nsec);
+	memset(cinode->ctime.__pad, 0, sizeof(cinode->ctime.__pad));
 	cinode->mtime.sec = cpu_to_le64(inode->i_mtime.tv_sec);
 	cinode->mtime.nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
+	memset(cinode->mtime.__pad, 0, sizeof(cinode->mtime.__pad));
 
 	cinode->meta_seq = cpu_to_le64(scoutfs_inode_meta_seq(inode));
 	cinode->data_seq = cpu_to_le64(scoutfs_inode_data_seq(inode));

kmod/src/key.h

@@ -78,6 +78,7 @@ static inline void scoutfs_key_set_zeros(struct scoutfs_key *key)
 	key->_sk_second = 0;
 	key->_sk_third = 0;
 	key->_sk_fourth = 0;
+	memset(key->__pad, 0, sizeof(key->__pad));
 }
 
 static inline bool scoutfs_key_is_zeros(struct scoutfs_key *key)
@@ -104,6 +105,7 @@ static inline void scoutfs_key_set_ones(struct scoutfs_key *key)
 	key->_sk_second = cpu_to_le64(U64_MAX);
 	key->_sk_third = cpu_to_le64(U64_MAX);
 	key->_sk_fourth = U8_MAX;
+	memset(key->__pad, 0, sizeof(key->__pad));
 }
 
 /*

kmod/src/net.c

@@ -369,6 +369,7 @@ static int submit_send(struct super_block *sb,
 	msend->nh.cmd = cmd;
 	msend->nh.flags = flags;
 	msend->nh.error = net_err;
+	memset(msend->nh.__pad, 0, sizeof(msend->nh.__pad));
 	msend->nh.data_len = cpu_to_le16(data_len);
 	if (data_len)
 		memcpy(msend->nh.data, data, data_len);

kmod/src/net.h

@@ -102,6 +102,7 @@ static inline void scoutfs_addr_from_sin(struct scoutfs_inet_addr *addr,
 {
 	addr->addr = be32_to_le32(sin->sin_addr.s_addr);
 	addr->port = be16_to_le16(sin->sin_port);
+	memset(addr->__pad, 0, sizeof(addr->__pad));
 }
 
 struct scoutfs_net_connection *

kmod/src/xattr.c

@@ -573,6 +573,7 @@ static int scoutfs_xattr_set(struct dentry *dentry, const char *name,
 			id = si->next_xattr_id++;
 		xat->name_len = name_len;
 		xat->val_len = cpu_to_le16(size);
+		memset(xat->__pad, 0, sizeof(xat->__pad));
 		memcpy(xat->name, name, name_len);
 		memcpy(&xat->name[xat->name_len], value, size);
 	}