[PATCH 09/14] xfs: validate recovered name buffers when recovering xattr items

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Strengthen the xattri log item recovery code by checking that we
actually have the required name and newname buffers for whatever
operation we're replaying.

Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/xfs_attr_item.c |   58 +++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 47 insertions(+), 11 deletions(-)


diff --git a/fs/xfs/xfs_attr_item.c b/fs/xfs/xfs_attr_item.c
index b4c2dcb4581b..ebd6e98d9c66 100644
--- a/fs/xfs/xfs_attr_item.c
+++ b/fs/xfs/xfs_attr_item.c
@@ -741,22 +741,20 @@ xlog_recover_attri_commit_pass2(
 	const void			*attr_value = NULL;
 	const void			*attr_name;
 	size_t				len;
-	unsigned int			op;
-
-	attri_formatp = item->ri_buf[0].i_addr;
-	attr_name = item->ri_buf[1].i_addr;
+	unsigned int			op, i = 0;
 
 	/* Validate xfs_attri_log_format before the large memory allocation */
 	len = sizeof(struct xfs_attri_log_format);
-	if (item->ri_buf[0].i_len != len) {
+	if (item->ri_buf[i].i_len != len) {
 		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
 				item->ri_buf[0].i_addr, item->ri_buf[0].i_len);
 		return -EFSCORRUPTED;
 	}
 
+	attri_formatp = item->ri_buf[i].i_addr;
 	if (!xfs_attri_validate(mp, attri_formatp)) {
 		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
-				item->ri_buf[0].i_addr, item->ri_buf[0].i_len);
+				attri_formatp, len);
 		return -EFSCORRUPTED;
 	}
 
@@ -785,31 +783,69 @@ xlog_recover_attri_commit_pass2(
 				     attri_formatp, len);
 		return -EFSCORRUPTED;
 	}
+	i++;
 
 	/* Validate the attr name */
-	if (item->ri_buf[1].i_len !=
+	if (item->ri_buf[i].i_len !=
 			xlog_calc_iovec_len(attri_formatp->alfi_name_len)) {
 		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
-				item->ri_buf[0].i_addr, item->ri_buf[0].i_len);
+				attri_formatp, len);
 		return -EFSCORRUPTED;
 	}
 
+	attr_name = item->ri_buf[i].i_addr;
 	if (!xfs_attr_namecheck(attr_name, attri_formatp->alfi_name_len)) {
 		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
-				item->ri_buf[1].i_addr, item->ri_buf[1].i_len);
+				attri_formatp, len);
 		return -EFSCORRUPTED;
 	}
+	i++;
 
 	/* Validate the attr value, if present */
 	if (attri_formatp->alfi_value_len != 0) {
-		if (item->ri_buf[2].i_len != xlog_calc_iovec_len(attri_formatp->alfi_value_len)) {
+		if (item->ri_buf[i].i_len != xlog_calc_iovec_len(attri_formatp->alfi_value_len)) {
 			XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
 					item->ri_buf[0].i_addr,
 					item->ri_buf[0].i_len);
 			return -EFSCORRUPTED;
 		}
 
-		attr_value = item->ri_buf[2].i_addr;
+		attr_value = item->ri_buf[i].i_addr;
+		i++;
+	}
+
+	/*
+	 * Make sure we got the correct number of buffers for the operation
+	 * that we just loaded.
+	 */
+	if (i != item->ri_total) {
+		XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
+				attri_formatp, len);
+		return -EFSCORRUPTED;
+	}
+
+	switch (op) {
+	case XFS_ATTRI_OP_FLAGS_REMOVE:
+		/* Regular remove operations operate only on names. */
+		if (attr_value != NULL || attri_formatp->alfi_value_len != 0) {
+			XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
+					     attri_formatp, len);
+			return -EFSCORRUPTED;
+		}
+		fallthrough;
+	case XFS_ATTRI_OP_FLAGS_SET:
+	case XFS_ATTRI_OP_FLAGS_REPLACE:
+		/*
+		 * Regular xattr set/remove/replace operations require a name
+		 * and do not take a newname.  Values are optional for set and
+		 * replace.
+		 */
+		if (attr_name == NULL || attri_formatp->alfi_name_len == 0) {
+			XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
+					     attri_formatp, len);
+			return -EFSCORRUPTED;
+		}
+		break;
 	}
 
 	/*